From what I gather, Japan's attack did come as a surprise. The two parties were at odds, but not to the point that a war was an immediate concern.

No doubt some in the government wanted to attack, no different than you could find who want to attack Iran in today's government, but it's not the US government's position. FDR was definitely more interested in getting involved internationally, but the Republicans were staunchly isolationist.

The comparison to Russia and Ukraine is there. Russia preemptively attacked Ukraine because it wanted to prevent NATO from getting a foothold in it's sphere of influence. Japan considering the Pacific Ocean and namely the resources in South East Asian there's, so preemptively attacked the US to prevent it from opposing it's control over the Pacific.