A follow-on from this very interesting thread regarding the U.S. Navy:
The question can be considered in relative or absolute terms and including or excluding nuclear weapons.
Thanks in advance. 
To a certain extent, I suppose it depends on how you define powerful. If powerful is defined as maximum offensive capability, I think the answer is now. Technology is an effective force multiplier, and we’ve got a high tech military capable of turning any particular spot on the planet into radioactive dust on very short notice. We can down-tune from there to put conventional bombs on target anywhere on the planet with somewhat longer notice.
What time is it now? The US military has never been more powerful than it is today… and next year it will be even more powerful as newer weapons and technologies are deployed. The US spends more money on it’s military hardware than any other country, and that’s how it’s been for quite a while.