Does China have an answer or counter to our nuclear submarines and their ballistic missiles? That's a nice trump card for us to have.
People might be interested in this, dated in year 1999:
http://www.worldnetdaily.com/news/article.asp?ARTICLE_ID=15233
So that's one area, laser weapons.
Assume the science fiction of nanotechnology is not science fiction, whichever country owns it first will dominate the world (in terms of developing it into a military program). US is the current leader in research, followed by China, Germany, Japan, Russia.
Hardly. They can't effectively map using sonar. In other words, our submarines won't show up on their screens unless A) They are actively searching the area the sub is parked in. B) The sub moves rapidly or does something violently loud.
When the sub does something violently loud, it's too late. Bedtime.