大衛·格蘭茨（David Glantz）在他的《巴巴羅薩：1941年希特勒對俄羅斯的入侵》中提到了幾個促成因素。協議。這是通常被帶出的最主要武器，但不是全部。

在活動結束後很容易找出本應警告蘇聯的情報。在確定時間之前，要確定您應該相信的許多對立智能中的哪些是錯誤信息或只是不准確（或者在更改計劃之前是準確的），要困難得多。查看當時可供斯大林使用的信息，也許讓他在1941年6月完全被驚呆了並不奇怪，儘管他的一廂情願也是其促成因素之一。

I don't know a ton about this topic, but in Molotov Remembers, a reprint of a bunch of conversations with Molotov in the 70s and 80s, the interviewer asks a lot of questions about this topic.

Molotov said that Stalin knew there would be war with Hitler, and the whole point of the Molotov-Ribbentrop Pact was to stall for time and prepare, and that Stalin felt the country needed two more years before the USSR was ready. Molotov makes clear that all of the ruling circle knew that the Nazis were enemies, and that they knew an attack was eminent. Molotov laughed at the idea that Stalin naively thought that Hitler could be trusted to keep the terms of the Pact - indeed he points out that Stalin trusted no one, even Molotov himself!

So why was the Soviet Union "caught by surprise" when the Germans attacked? Molotov says that Stalin was primarily worried about an anti-USSR German/British alliance, and that Stalin sent orders to his troops specifically to make sure that Germany was the clear aggressor. The orders specified that there was to be no military response to anything the Germans did, except from Stalin himself.

Prior to the invasion, there was a number of border skirmishes and false alarms. Molotov says they were worried about being baited by Hitler into escalating the war, and thus be blamed for its start. The orders helped delay the start of the war by weeks or months. He also mentioned the British intelligence report and that they felt it was something of a joke, that "how could we not know the invasion was eminent? And how could we trust the British?"

Molotov then goes on to call Stalin a genius for this tactic, because:

1. The delayed the start of the war allowed winter to interrupt the German invasion, ultimately preventing defeat.
2. That showing that Germany was the aggressor split the German/British/capitalist alliance, and even causing the counter-intuitive US/British/Soviet alliance. Molotov states that receiving material help from the US was unthinkable in the 1930s, and that only Stalin could have conceived of this plan.

Just to be clear, I have not read enough about this subject to give a full answer, having only read Molotov's biased opinion. I am not sure I fully buy his opinion, considering what he said about the Holodomor. However, I feel he is correct in stating that the USSR would have lost if the invasion had started even 1 month earlier. I also liked his point about how odd the idea of an alliance with the British was.

On another note, it was interesting to hear his first hand account of what all the major actors in WWII were like personally; he didn't like Ribbentrop very much!

Stalin received a large number of contradictory puzzle pieces. He and his intelligence analysts believed the information which suggested no attack yet and disbelieved the information which suggested an immediate attack.

• Stalin and his immediate circle must be blamed for creating a dysfunctional intelligence system, where analysts could not contradict the preconceived notions of the boss. Compare the recent Gulf War intelligence failure.
• Germany had a rather chaotic system of making policy, which explains why it was difficult to discern. That explanation falls flat in the last days before the attack.

I have read all the interesting answers and I want to propose a somewhat different way to look at this problem. By the way, this mistake of Stalin had cost millions of lives so the question is really important.

I believe, as did Molotov who experienced it firsthand, that Stalin was a genius of the first caliber. An evil genius, surely, but a political genius like no other. He controlled everything, he saw further and deeper than everybody and he was a practical and extremely ruthless leader and organizer. Even Churchill, who hated communism deeply, spoke of Stalin in such terms.

Stalin had the best intelligence service ever. Communists and communist sympathysers were everywhere and many of them were Comintern agents. He had informers in the German foreign office and General staff of the army. He was well informed on the German economy, the size of its army, its armour, the size of its air-force (Luftwaffe). He knew very well that the German tanks are greatly inferior to the Russian tanks. And he believed, crucially, that for Hitler to attack Russia would be suicidal. In this he was right of course, but still it was close. There were moments in 1941 and the summer of 42 when many in the west and perhaps also in Russia thought that the Wehrmacht is winning.

So why did he make his awful error? Hitler's chain of successes, culminating in the easy defeat of the British and French in 1940 left an impression in Stalin's cunning and calculating mind. "Perhaps the guy is not just a fanatical ideologue and adventurous gambler. He clearly has an excellent army so one can assume that his great gambles were based on a rational calculation". If so then Hitler would surely understand that attacking Russia is too dangerous and could even be suicidal!

So, Stalin's mistake was, in my opinion, that he gave Hitler too much credit. They were both representatives of the devil on earth but Stalin was by far the more able man.

Finally I would like very much to know what you think of my suggestions. I have been pondering this for a long time and am eager to discuss the matter.

罪魁禍首蘇沃洛夫（海軍學院出版社，2008年，第248-9頁）

高利科夫對明顯錯誤情報的有罪不罰一直使我個人擔心很久，直到我參加在GRU學院講課。後來，當我在GRU的中央機構工作時，發現對這個答案的確認。

Golikov曾經向斯大林報告希特勒沒有為與蘇聯的戰爭做準備。事實證明，由於希特勒沒有做好準備，戈利科夫正在向斯大林報告真相。戈利科夫知道斯大林不信任文件。戈利科夫也不信任他們。因此，他尋找其他指標，這些指標將毫不動搖地表示希特勒開始為與蘇聯開戰的時刻。沒有做任何準備。因此，斯大林沒有理由懲罰戈利科夫。戈利科夫竭盡全力發現了德國的戰爭準備。他告訴斯大林沒有任何準備工作，這是事實。德國軍隊只有大量的集結。戈利科夫（Golikov）發出指示，並非所有的德國師都必須成為關注的對象，而只有那些準備入侵的師。這些部門的倉庫中有15,000件羊皮大衣。整個國防軍中根本沒有這樣的師準備戰鬥。

因為他正忙於攻擊羅馬尼亞

https://en.m.wikipedia.org/wiki/Soviet_occupation_of_Bessarabia_and_Northern_Bukovina

其他牧師被蘇聯NKVD本身逮捕和審訊，然後驅逐到蘇聯內部並被殺害。關於該主題的研究仍處於早期階段。自2007年起，基督教東正教教堂已將to難授予約50名神職人員在蘇維埃統治的第一年（1940年至1941年）去世。[86

Stalin failed to be objective. Leaders of totalitarian regimes often seem to suffer from this defect. Stalin was the center of a system where he didn't need to be objective and that revolved around his wishes. Absolute power tends to erode one objectivity. The prevalence of yes men and a reluctance to bring evidence that the supreme leader, conclusions counter to the leader's desires are just not presented forcefully. Stalin was used to a situation where he could almost control the facts, reality for most Russians was what Stalin said it was, fear of Stalin was greater than fear of getting things wrong. Stalin didn't want to face the facts that the had got things wrong, the system he was the center of was very much an enabler of Stalin's desires.

希特勒不久前發現了一些信件，他在信中寫道斯大林說，他只是在英國皇家空軍無法到達他們的邊境建立了一支部隊。他還從幾位高級蘇維埃報導中獲悉希特勒會發動進攻，但也有一個說法相反，斯大林和一些高級蘇維埃部長（或某物）都相信希特勒的行為。害怕信任周圍的任何人。
我必須在家中查找消息來源和名字。因此，如果第二天我有時間，我會發送給他們。

沒人知道襲擊的確切日期。情報提供了不同的數據。然而，在6月初，潛在的動員開始了。部分師被派往邊境。斯大林正在等待入侵。他正在為國家做準備。斯大林相信希特勒？不，準備戰爭了嗎？是的，紅軍準備好了嗎？不不不。絕對不。整裝待發於1942年。斯大林對紅軍的失敗感到驚訝？我覺得不行。 “冬季戰爭”表明了圖哈切夫斯基軍事理論的錯誤。紅軍還沒有為戰爭做好準備。國防軍更強大。