In the April 2002 issue of Wired, SF author Bruce Sterling proposed a number of ways to destroy America's dominance in the international community, based on the idea that America's greatest asset is its communications/spy satellite network. Seven of his scenarios involve outer space, and the others involve the terra firma. Here's an executive summary of his twelve ideas:

1. "Build Your Own," i.e. duplicate America's space assets. This was the original plan of the Soviets, but they ultimately failed at it... China is trying it now with slow success, and American space superiority may be challenged by Europe, Japan, or even some Middle Eastern countries if funding is allowed to dwindle.
2. Detonate a nuke at high altitude to disable American satellites. EMP attacks in space may be possible for the next few years before boost-phase missile defense systems go into operation.
3. Put tiny satellites in space to disassemble American communications. (Doesn't that reek of bad sci-fi?)
4. Throw sand into space to chop up American satellites. (Doesn't that reek of bad RPG's?)
5. Hack American satellites from the ground. Although Chinese and Russian hackers have been in the news so often as to make the public uneasy, hacking a defense or communications satellite is a very improbable task unless you have access to a government ground station, or unless the original programmers have put back doors in the software. (Either way, it's not an implausible idea if someone happens to put the right social engineering skills to work.)
6. Put electronic noisemakers in space to overpower American satellites. Sterling notes the obvious flaw in this idea: a satellite giving off this much interference would be very easy to home in on and destroy.
7. Shoot down satellites via laser/particle beam. (Need I even mention how badly this reeks of sci-fi?)
8. Drive a truck nuke into Washington. (Why didn't Al-Qaeda try this? I honestly don't know.)
9. Destroy the American communications network from below: i.e. ground stations, land lines, etc.
10. Bribe American ground operators... similar idea to 5. above, except more plausible than a remote hacker attack.
11. Avoid space and go to nuclear weapons or terrorism. Then again, this is what America is expecting, isn't it?
12. Wait it out and let the United States collapse on its own.

The article is really very good reading, even if it is a bit farfetched at times, and comes with this noder's recommendation.