To be fair, my idea of a suicide bomber in an invasion of America is a bit different than a dude strapping TNT to his chest, and blowing himself up in a market place.
When I say suicide bomber, I mean someone that risks life and limb to defeat the invasion force. We have plentiful guns in America, but they wouldn't do anything against a nice T-90 or Leopard MBT. That is why I mentioned suicide bombings. I'd imagine that taking a C or D-class truck filled with explosives and driving it into an enemy strongpoint would be a worthy cause. Again, I'm not endorsing the cowardice of terrorists like what we liken to suicide bombers - to attack innocent bystandards - but take radical risks against a standing army.
Of course, I'd try not to risk life, and figure out how to accomplish such tasks by proxy, but still...I'd rather die knowing that I tried to fend off an invasion than die slowly under massive opression and human rights abuses, knowing that my family and friends met a horrible fate.
Actually, I know a good few people who have some firepower that isn't totally legal to own that can take out a few tanks and planes with ease. Plus my local gun shop has a lovely 50cal sniper rifle that should be able to punch a hole into a tank's cockpit since it is an anti tank gun.