Readers may have a look at the assessments I referred to and judge for themselves:
William Shirer (The Rise and Fall of the Third Reich, New York 1960, pages 795 and following) wrote:[...] It is clear from his acts and from the secret German papers that though Stalin was out to get all he could in Eastern Europe while the Germans were tied down in the West, he did not wish or contemplate a break with Hitler.
Toward the end of June  Churchill had tried to warn Stalin in a personal letter of the danger of the German conquests to Russia as well as to Britain. The Soviet dictator did not bother to answer; probably, like everyone else, he thought Britain was finished. So he tattled to the Germans what the British government was up to. Sir Stafford Cripps, a left-wing Labor Party leader, whom the Prime Minister had rushed to Moscow as the new British ambassador in the hope of striking a more responsive chord among the Bolsheviks - a forlorn hope, as he later ruefully admitted - was received by Stalin early in July in an interview that Churchill described as “formal and rigid.” On July 13 Molotov, on Stalin’s instructions, handed the German ambassador a written memorandum of his confidential conversation.
It is an interesting document. It reveals, as no other source does, the severe limitations of the Soviet dicator in his cold calculations of foreign affairs. Schulenburg sped it to Berlin “most urgent” and, of course, “secret”, and Ribbentrop was so grateful for its contents that he told the Soviet government he “greatly appreciated this information”. Cripps had pressed Stalin, the memorandum said, for his attitude on this principal question, among others:
The British government was convinced that Germany was striving for hegemony in Europe . . . This was dangerous to the Soviet Union as well as England. Therefore both countries ought to agree on a common policy of self-protection against Germany and on the re-establishment of the European balance of power ...
Stalin’s answers are given as follows:
He did not see any danger of the hegemony of any one country in Europe and still less any danger that Europe might be engulfed by Germany. Stalin observed the policy of Germany, and knew several leading German statesmen well. He had not discovered any desire on their part to engulf European countries. Stalin was not of the opinion that German military successes menaced the Soviet Union and her friendly relations with Germany ...
Such staggering smugness, such abysmal ignorance leave one breathless. The Russian tyrant did not know, of course, the secrets of Hitler’s turgid mind, but the Führer’s past behavior, his known ambitions and the unexpectedly rapid Nazi conquests ought to have been enough to warn him of the dire danger the Soviet Union was now in. But, incomprehensibly, they were not enough.
From the captured Nazi documents and from the testimony of many leading German figures in the great drama that was being played over the vast expanse of Western Europe that year, it is plain that at the very moment of Stalin’s monumental complacency Hitler had in fact been mulling over in his mind the idea of turning on the Soviet Union and destroying her.
The basic idea went back much further, at least fifteen years - to Mein Kampf.
And so we National Socialists [Hitler wrote] take up where we broke off six hundred years ago. We stop the endless German movement toward the south and west of Europe and turn our gaze toward the lands of the East ... when we speak of new territory in Europe today we must think principally of Russia and her border vassal states. Destiny itself seems to wish to point our the way to us here ... This colossal empire in the East is ripe for dissolution, and the end of the Jewish domination in Russia will also be the end of Russia as a state.
This idea lay like bedrock in Hitler’s mind, and his pact with Stalin had not changed it at all, but merely postponed acting on it. And but briefly. In fact, less than two months after the deal was signed and had been utilized to destroy Poland, the Führer instructed the Army that the conquered Polish territory was to be regarded “as an assembly area for future German operations.” The date was October 18, 1939, and Halder recorded that day in his diary.
Five weeks later, on November 22, when he harangued his reluctant generals about attacking in the West, Russia was by no means out of his mind. “We can oppose Russia,” he declared, “only when we are free in the West.” At that time the two-front war, the nightmare of German generals for a century, was very much on Hitler’s mind, and he spoke of it at length on this occasion. He would not repeat the mistake of former German rulers; he could continue to see to it that the Army had one front at a time.
It was only natural, then, that with the fall of France, the chasing of the British Army across the Channel and the prospects of Britain’s imminent collapse, Hitler’s thoughts should turn once again to Russia. For he now supposed himself to be free in the West and thereby to have achieved the one condition he had laid down in order to be in a position to “oppose Russia.” the rapidity with which Stalin seized the Baltic States and the two Romanian provinces in June spurred Hitler to a decision.
The moment of its making can now be traced. Jodl says that the “fundamental decision” was taken “as far back as during the Western Campaign.” Colonel Walter Warlimont, Jodl’s deputy at OKW, remembered that on July 29 Jodl announced at a meeting of Operations Staff officers that “Hitler intended to attack the U.S.S.R. in the spring of 1941.” Sometime previous to this meeting, Jodl related, Hitler had told Keitel “that he intended to launch the attack against the U.S.S.R. during the fall of 1940.” But this was too much even for Keitel and he had argued Hitler out of it by contending that not only the bad weather in the autumn but the difficulties of transferring the bulk of the Army from the West to the East made it impossible. By the time of this conference on July 29, Warlimont relates, “the date for the intended attack [against Russia] had been moved back to the spring of 1941.”
Only a week before, we know from Halder’s diary, the Führer had still held to a possible campaign in Russia for the autumn if Britain were not invaded. At a military conference in Berlin on July 21 he told Brauchitsch to get busy on the preparations for it. That the Army Commander in Chief had already given the problem some thought - but not enough thought - is evident from his response to Hitler. Brauchitsch told the Leader that the campaign “would last four to six weeks” and that the aim would be “to defeat the Russian Army or at least to occupy enough Russian territory so that Soviet bombers could not reach Berlin or the Silesian industrial area while, on the other hand, the Luftwaffe bombers could reach all important objectives in the Soviet Union.” Brauchitsch thought that from eighty to a hundred German divisions could do the job; he assessed Russian strength at “fifty to seventy-five good divisions.” Halder’s notes on what Brauchitsch told him of the meeting show that Hitler had been stung by Stalin’s grabs in the East, that he thought the Soviet dictator was “coquetting with England” in order to encourage her to hold out, but that he had seen no signs that Russia was preparing to enter the war against Germany.
At a further conference at the Berghof on the last day of July 1940, the receding prospects of an invasion of Britain prompted Hitler to announce for the first time to his Army chiefs his decision on Russia. Halder was personally present this time and jotted down his shorthand notes of exactly what the warlord said. They reveal not only that Hitler had made a definite decision to attack Russia in the following spring but that he had already worked out in his mind the major strategic aims.
Britain’s hope [Hitler said] lies in Russia and America. If that hope in Russia is destroyed then it will be destroyed for America too because elimination of Russia will enormously increase Japan’s power in the Far East.
The more he thought of it the more convinced he was, Hitler said, that Britain’s stubborn determination to continue the war was due to its counting on the Soviet Union.
Something strange [he explained] has happened in Britain! The British were already completely down. Now they are back on their feet. Intercepted conversations. Russia unpleasantly disturbed by the swift development in Western Europe.
Russia needs only to hint to England that she does not wish to see Germany too strong and the English, like a drowning man, will regain hope that the situation in six to eight months will have completely changed.
But if Russia is smashed, Britain’s last hope will be shattered. Then Germany will be master of Europe and the Balkans.
Decision: In view of these considerations Russia must be liquidated. Spring, 1941.
The sooner Russia is smashed, the better.
The Nazi warlord then elaborated on his strategic plans which, it was obvious to the generals, had been ripening in his mind for some time despite all his preoccupations with the fighting in the West. The operation, he said, would be worth carrying out only if its aim was to shatter the Soviet nation in one great blow. Conquering a lot of Russian territory would not be enough. “Wiping out the very power to exist of Russia! That is the goal!” Hitler emphasized. There would be two initial drives: one in the south to Kiev and the Dnieper River, the second in the north up through the Baltic States and then toward Moscow. There the two armies would make a junction. After that a special operation, if necessary, to secure the Baku oil fields. The very thought of such new conquests excited Hitler; he already had in his mind what he would do with them. He would annex outright, he said, the Ukraine, White Russia and the Baltic States and extend Finland’s territory to the White Sea. For the whole operation he would allot 120 divisions, keeping sixty divisions for the defense of the West and Scandinavia. The attack, he laid it down, would begin in May 1941 and would take five months to carry through. It would be finished by winter. He would have preferred, he said, to do it this year but this had not proved possible.
The next day, August 1, Halder went to work on the plans with his General Staff. Though he would later claim to have opposed the whole idea of an attack on Russia as insane, his diary entry for this day discloses him full of enthusiasm as he applied himself to the challenging new task.
Planning now went ahead with typical German thoroughness on three levels: that of the Army General Staff, of Warlimont’s Operations Staff at OKW, of General Thomas’ Economic and Armaments Branch of OKW. Thomas was instructed on August 14 by Göring that Hitler desired deliveries of ordered goods to the Russians “only till spring of 1941.” In the meantime his office was to make a detailed survey of Soviet industry, transportation and oil centers both as a guide to targets and later on as an aid for administering Russia.
A few days before, on August 9, Warlimont had got out his first directive for preparing the deployment areas in the East for the jump-off against the Russians. On August 26, Hitler ordered ten infantry and two armored divisions to be sent from the West to Poland. The panzer units, he stipulated, were to be concentrated in southeastern Poland so that they could intervene to protect the Romanian oil fields. The transfer of large bodies of troops to the East could not be done without exciting Stalin’s easily aroused suspicions if he learned of it, and the Germans went to great lengths to see that he didn’t. Since some movements were bound to be detected, General Ernst Köstring, the German military attaché in Moscow, was instructed to inform the Soviet General Staff that it was merely a question of replacing older men, who were being released to industry, by younger men. On September 6, Jodl got out a directive outlining in considerable detail the means of camouflage and deception. “These regroupings,” he laid it down, “must not create the impression in Russia that we are preparing an offensive in the East.”
So that the armed services should not rest on their laurels after the great victories of the summer, Hitler issued on November 12, 1940, a comprehensive top-secret directive outlining military tasks all over Europe and beyond. We shall come back to some of them. What concerns us here is that portion dealing with the Soviet Union.
Political discussions have been initiated with the aim of clarifying Russia’s attitude for the time being. Irrespective of the results of these discussions, all preparations for the East which have already been verbally ordered will be continued. Instructions on this will follow, as soon as the general outline of the Army’s operation plans have been submitted to, and approved by, me.
As a matter of fact, on that very day, November 12, Molotov arrived in Berlin to continue with Hitler himself those political discussions.
Emphases are mine.
Richard Overy (Russia's War, Penguin Books 1998, pages 61 and following) wrote:[….] The sudden expansion of Soviet territory westward, although conceded in principle in 1939, produced fresh anxieties in Berlin. The Soviet-Finnish war had left Germany in a difficult position, for her sympathies were with the Finns. After the end of the war German troops were stationed in Finland. The deliveries of machinery and weapons to the Soviet Union agreed upon in the pact were slow and irregular, in sharp contrast with the scrupulous provision by the Soviet side of materials and food. Despite constant Soviet complaints, the German suppliers dragged their heels whenever they could rather than allow the latest technology fall into Russian hands. From Hitler’s point of view the most unfortunate consequence of the pact was the rapid forward deployment of the Red Army in Eastern Europe. He was embroiled in a major war, which he had not wanted and which the pact had been supposed to avert. Now, instead of a powerful Germany dominating Eastern and Central Europe following Poland’s defeat, Germany was engaged in an unpredictable war against the British Empire, while the Soviet Union was free to extend its influence unchecked. The occupation of Bessarabia was a final blow. A few weeks later Goebbels wrote in his diary: ‘Perhaps we shall be forced to take steps against all this, despite everything, and drive this Asiatic spirit back out of Europe and into Asia, where it belongs.’
Hitler had anticipated him. On July 3 ,instructions were issued to the German armed forces, under the code name ‘Fritz’, to begin preliminary studies for an operation against the Soviet Union. At first the army believed that Hitler wanted to inflict only a local defeat on Soviet forces so as to push back the frontier between them and force Stalin to recognize ‘Germany’s dominant position in Europe’. The army told Hitler on July 21 that a limited campaign could be launched in four to six weeks. But Hitler’s ideas, which had at first been uncertain, hardened over the course of the month, as a stream of intelligence information came in showing how Soviet diplomats were now pushing into the Balkans in their efforts to spread Soviet influence. When Hitler’s Operations Chief, General Alfred Jodl, called together his senior colleagues on July 29, he had the most startling news. After making sure that every door and window in the conference room aboard a specially converted train was tightly sealed, he announced that Hitler had decided to rid the world ‘once and for all’ of the Soviet menace by a surprise attack scheduled for May 1941.
There can be no doubt that practical strategic issues did push Hitler towards the most radical of military solutions. But a great war in the East had always been part of his thinking. Here was the real stuff of Lebensraum – living space. Hitler’s plans assumed fantastic proportions. By August he had decided to seize the whole vast area stretching from Archangel to Astrakhan (the ‘A-A Line’) and to populate it with fortified garrison cities, keeping the population under the permanent control of the master race, while a rump Asian state beyond the Urals, the Slavlands, would accommodate the rest of the Soviet people. Planning moved forward on this basis. By the spring of 1941 comprehensive programmes for the racial, political and economic exploitation of the new empire had been drawn up. ‘Russia’, Hitler is reported as saying, ‘will be our India!’.