There is a idea here that Congress will not vote for a declaration of war if Japan only attacks the Common wealth & DEI. But consider...When France collapsed in June Congress passed the War Powers Acts which mobilized the Army & Navy reserves, Federalized the National Guard, allocated a military expansion budget that ran counter to the fiscal policy of 75% of the Congressional members (deficit spending).
When Japan occupied French Indo China Congress authorized the Embargo Acts, which froze all Japanese finical assets in the US banks, denying Japan access to credit & crippling its ability to conduct international trade, denied Japan the use of foreign flagged cargo ships (40-50% of cargos passing through Japans ports were carried in foreign flagged hulls). These two actions alone were more crippling to Japans economy than the damage a few hundred B17s might have done in 1941-42. They also hurt US business, nevertheless Congress acquiesced to this very risky embargo plan.
As tensions rose the War Dept was able to move ahead with a large scale plan to reinforce the US Army (not just the PI Army) in the Phillipines. Advanced bases on Wake & Midway were established and fortification construction started, the Pacific fleet rebased to Oahu. Intelligence sharing was established between the Dutch, Commonwealth, and US commands in the Pacific. War planning also occurred between these commands. Admiral Phillps visited the PI & conferred with MacArthur 6th December.
All this occurred with declining opposition from Congress. The multiple polls taken show the US voters had in the autumn of 1941 accepted the idea the US would soon be at war with Japan, that the US would be increasing its aid to the British/Dutch.
Aside from US naval & air patrols across the Japanese lines of communications, US cargo ships were present in Dutch East Indies and Commonwealth ports. Its unrealistic to think there will be some incident or other involving a US war or cargo ship. There are likely to be a dozen such in the opening weeks as the Japanese attack ports and ships at sea.