Neither Churchill nor Patton advocated immediately attacking the Soviet Union.
Churchill ordered a basic level of planning for possible war (in 1945) with the Soviet Union. Two sets of plans were developed, both called Operation Unthinkable. The first was for a British-American-Polish offensive. The main probable goal would have been to ensure the existence of an independent Poland. As the plan documents put it:
The overall or political object is to impose upon Russia the will of the United States and British Empire.
Even though "the will" of these two countries may be defined as no more than a square deal for Poland, that does not necessarily limit the military commitment. A quick success might induce the Russians to submit to our will at least for the time being; but it might not. That is for the Russians to decide. If they want total war, they are in a position to have it.
The second plan was defensive, evaluating Soviet capability to threaten Western Europe, and Britain in particular. The stated purpose was:
we have considered what measures would be required to ensure the security of the British Isles in the event of war with Russia in the near future.
Plans, especially at this preliminary level, do not indicate intent. Countries routinely draft plans to invade their neighbours and allies, and to defend against attack by their neighbours and allies. First, such planning is good training for those who might need to do such planning in wartime. Second, if, in many years, such a war happens, an existing plan can be the basis of a new, "real" plan. Given that Churchill did not trust the Soviet Union, or Stalin, Operation Unthinkable was closer to possibility than, say, US plans to invade Canada in the 1930s (War Plan Red) and the Canadian plans to invade the US in the 1920s (Defence Scheme No. 1). However, Operation Unthinkable was still hypothetical, and does not reflect any intent or desire for war with the Soviet Union. Churchill's comment on the plans was
By retaining the codeword "UNTHINKABLE", the Staffs will realise that this remains a precautionary study of what, I hope, is still a purely hypothetical contingency.
The conclusion, by the way, of Operation Unthinkable was
Our view is, therefore, that once hostilities began, it would be beyond our power to win a quick but limited success and we should be committed to a protracted war against heavy odds. These odds, moreover, would become fanciful if the Americans grew weary and indifferent and began to be drawn away by the magnet of the Pacific War.
For the original documents, see
from which the above quotes were taken.
Like Churchill, Patton distrusted the Soviets. On 17th May, the US forces in Europe were preparing to put pressure on Tito. As Patton wrote in his diary,
... Tito is raising hell at the north end of the Adriatic, and General Marshall had telegraphed General Eisenhower that it was necessary to use the prestige of my name and the Third Army and at least five armored divisions to bluff him.
Patton continued in his diary the next day:
The question at issue is not so much Tito but as to whether or not he is the pawn of the Russians and, if so, whether he is being used as a red herring to pull us to the south so that the Russians may resume an offensive in Central Germany; or whether the Russians are actually backing Tito with the idea of getting a port, or ports, on the northern end of the Adriatic. The situation should clarify itself within a few days. If it does not, considerable complication will arise on redeployment.
In my opinion, the American Army as it now exists could beat the Russians with the greatest of ease, because while the Russians have good infantry, they are lacking in artillery, air, tanks, and in their knowledge of the use of the combined arms; whereas we excel in all three of these. If it should be necessary to fight the Russians, the sooner we do it the better.
... I believe that by taking a strong attitude, the Russians will back down. So far we have yielded too much to their Mongolian nature.
Patton (a) distrusted Soviet aims, and (b) felt that the US had an advantage if it came to war with the Soviet Union, and (c) that advantage would decrease with time. However, he did not advocate such a war, and did not want to fight the Soviets. He felt that the US should negotiate from a position of strength, if necessary supported by the threat of force. He believed that this would result in Soviet compliance without war.
Patton's diaries are available online:
The above quotes come from pages 27 and 28 in this section:
The Soviets prepared plans for war with the West. Again, this doesn't mean that there was any intent for war against the West. However, at least some of their plans may have gone beyond the hypothetical level of Operation Unthinkable, possibly in response to intelligence reports about Operation Unthinkable. When Operation Unthinkable became public knowledge in 1998, historian John Erickson (author of The Road to Stalingrad and The Road to Berlin), commented
On June 29, 1945, the Red Army suddenly executed a complete redeployment of its order of battle, for no apparent reason. I have always wondered why they did it. I have asked Soviet staff officers about it and never been able to understand their thinking. Perhaps we have just discovered the explanation.
Notably, the hypothetical start date of the attack version of Operation Unthinkable was 1st July 1945.
Reference:
John Erickson quote from