Russia - Economically handicapped with poor industry
China - 1 billion people in subsaharan poverty, a restless population, and horrible economic troubles
both countries don't have a navy that even compares to the U.S.
U.S. controls international shipping
about the only thing Russia has is the largest stockpile of nukes
China is far ahead and will be dominating the US for a long time, the american economy has no hope of recovering and their currency is soon to be worth less than dirt, Navies have nothing to do with anything, China can easily destroy what remains of the US economy by simply not sending it anymore products.
US doesn't have as much to do with world wide trade as you think.
Lastly if the US was to attack because of trade and economic debt and trouble, they would dig themselves deeper because nobody would want to trade with a nation that instead of repaying debts tried to fight.
America is already doomed and will undoubtedly collapse completely in the next few years.