I'll see what I can do.
Under your example suicide attacks by U.S. troops against terrorists would have escalated in proportion because of our being there.
Whoa, no fair. You just made the rule, and now you're cheating.
The reason they haven't is because suicide attacks are not a weapon of sane and rationale people...in other words, it is the result of the Islamic fundamentalism not occupation or warfare
If that's the case, then explain this:
If suicide bombing was caused only by Islamic extremism, then there would have been no statisitcal difference from the rate of incidents pre and post invasion Iraq. We're no more or less infidel now than we were then. Whether or not we agree with it, the perception in the Arab world is that we're a foriegn invading army in the heart of the Arab wrold, and that propaganda is what's used to induce new recruits. Otherwise, we'd have seen far more before Iraq, and we'd be seeing suicide bombers in places other than Iraq.
Incorrect. Correlation does not imply causation. In addition, it is up to the claimant (i.e. YOU) to prove there is a causative link, not others to prove there isn't (see the logical fallacy: shifting the burden of proof).
There are many reasons, independant of territorial concerns, that would explain an increase in suicide bombings in Iraq. First, it might be closer to the bombers, thereby making it easier for them to bomb (it's much harder to slip a terrorist with explosives into the US... plus, the closer to the bad guys, the more of them that will be able/willing to attack). Or the terrorists might see suicide bombing as a more viable tactic (based on local conditions) there than here. Or the increase in attacks might be a sign that the terrorists are afraid their religious, cultural, or political goals are in danger of failing, and they could be a sign of desparation. The Japanese didn't start the war with banzai charges and kamikazes; only after their supplies and escape routes were cut off or when they had run out of trained pilots did they resort to suicide attacks.
There are many plausible explanations for the increase in suicide bomobings in Iraq that have little to do with territorial concerns (especially since many of the terrorists and bombers are being shipped in to Iraq in the first place...). It is your job to prove that their motivation is purely territorial, which so far you have shown little persuasive evidence for...