Americans being critical of the performance of other countries in the 1939-41 period always bring out a wan smile on the face of the average European who knows their history. As Winston Chruchill pointed out, no country in the democratic camp bears heavier responsibility for the war than America.
This is a little too strong and is historical nonsense. WWII as well as WWI was the end (for the time being) of a Euro centric world where most of the economic and military power was concentrated in Europe. These wars were due to the total failure of European diplomacy and the ultra nationalism of the various European powers. The US bailed out Britain and France twice in the first half of the the 20th century and between the wars Europe basically went back to business as usual after the first world war and shunned US recommendations at the time of the peace conference (Wilson by that time was an incapacitated President) and not feeling particularly wanted or willing to play the game that was failing we went home and did our own thing. Some of our own things made have made the economic situation in the world worse but we weren't alone in our policies there either and were also suffering. We also did not have a particularly good record in responding to some of the things that we can't talk about in this forum on either a humanitarian or diplomatic basis. While the US had tremendous economic potential it had essentially no military projection capability in the pre WWII decade and also minimal capability to give economic aid.