http://www.ihr.org/jhr/v14/v14n6p19_chamberlin.html
American involvement in war with Germany was preceded by a long series of steps, not one of which could reasonably be represented as conducive to the achievement of the President's professed ideal of keeping the United States out of foreign wars. The more important of these steps may be briefly listed as follows:
The exchange of American destroyers for British bases in the Caribbean and in Newfoundland in September, 1940. This was a clear departure from the requirements of neutrality and was also a violation of some specific American laws. Indeed, a conference of top government lawyers at the time decided that the destroyer deal put this country into the war, legally and morally.
The enactment of the Lend-Lease Act in March, 1941. In complete contradiction of the wording and intent of the Neutrality Act, which remained on the statute books, this made the United States an unlimited partner in the economic war against the Axis Powers all over the world.
The secret American-British staff talks in Washington in January-March, 1941. Extraordinary care was taken to conceal not only the contents of these talks but the very fact that they were taking place from the knowledge of Congress. At the time when administration spokesmen were offering assurances that there were no warlike implications in the Lend-Lease Act, this staff conference used the revealing phrase, "when the United States becomes involved in war with Germany."
The inauguration of so-called naval patrols, the purpose of which was to report the presence of German submarines to British warships, in the Atlantic in April, 1941.
The dispatch of American laborers to Northern Ireland to build a naval base, obviously with the needs of an American expeditionary force in mind.
The occupation of Iceland by American troops in July, 1941. This was going rather far afield for a government which professed as its main concern the keeping of the United States out of foreign wars.
The Atlantic Conference of Roosevelt and Churchill, August 9-12, 1941. Besides committing America as a partner in a virtual declaration of war aims, this conference considered the presentation of an ultimatum to Japan and the occupation of the Cape Verde Islands, a Portuguese possession, by United States troops.
The orders to American warships to shoot at sight at German submarines, formally announced on September 11. The beginning of actual hostilities may be dated from this time rather than from the German declaration of war, which followed Pearl Harbor.
The authorization for the arming of merchant ships and the sending of these ships into war zones in November, 1941.
The freezing of Japanese assets in the United States on July 25, 1941. This step, which was followed by similar action on the part of Great Britain and the Netherlands East Indies, amounted to a commercial blockade of Japan. The warmaking potentialities of this decision had been recognized by Roosevelt himself shortly before it was taken. Addressing a delegation and explaining why oil exports to Japan had not been stopped previously, he said: "It was very essential, from our own selfish point of view of defense, to prevent a war from starting in the South Pacific. So our foreign policy was trying to stop a war from breaking out down there.... Now, if we cut the oil off, they [the Japanese] probably would have gone down to the Netherlands East Indies a year ago, and we would have had war."
When the Japanese Prime Minister, Prince Fumimaro Konoye, appealed for a personal meeting with Roosevelt to discuss an amicable settlement in the Pacific, this appeal was rejected, despite the strong favorable recommendations of the American ambassador to Japan, Joseph C. Grew.
Final step on the road to war in the Pacific was Secretary of State Hull's note to the Japanese government of November 26. Before sending this communication Hull had considered proposing a compromise formula which would have relaxed the blockade of Japan in return for Japanese withdrawal from southern Indochina and a limitation of Japanese forces in northern Indochina.
However, Hull dropped this idea under pressure from British and Chinese sources. He dispatched a veritable ultimatum on November 26, which demanded unconditional Japanese withdrawal from China and from Indochina and insisted that there should be "no support of any government in China other than the National government [Chiang Kai-shek]." Hull admitted that this note took Japanese-American relations out of the realm of diplomacy and placed them in the hands of the military authorities.
The negative Japanese reply to this note was delivered almost simultaneously with the attack on Pearl Harbor. There was a strange and as yet unexplained failure to prepare for this attack by giving General Short and Admiral Kimmel, commanders on the spot, a clear picture of the imminent danger. As Secretary of War Stimson explained the American policy, it was to maneuver the Japanese into firing the first shot, and it may have been feared that openly precautionary and defensive moves on the part of Kimmel and Short would scare off the impending attack by the Japanese task force which was known to be on its way to some American outpost.
Here is the factual record of the presidential words and the presidential deeds. No convinced believer in American nonintervention in wars outside this hemisphere could have given the American people more specific promises than Roosevelt gave during he campaign of 1940. And it is hard to see how any President, given the constitutional limitations of the office, could have done more to precipitate the United States into war with Germany and Japan than Roosevelt accomplished during the 15 months between the destroyer-for-bases deal and the attack on Pearl Harbor.