Americans are targets simply because we're Americans. Our main enemy -- Osama bin Laden and his ilk -- chose to be our enemy long before 9/11, and long before you began marching for "peace in our time."
It doesn't matter to our main enemy whether you're an anarchist, crypto-anarchist, libertarian, fascist, Democrat, or Republican. Which "side" you choose doesn't matter to our main enemy -- unless you choose to be on his side as an active member of his terrorist team, or unless you elect a president who is likely to walk away from the fight. That's the choice he wants from you: to walk away from the fight.
The only ideology our main enemy values is fundamentalist Islam, and he would impose a fundamentalist Islamic state upon you if he could. But he may settle for the retreat of the United States from the Middle East. In that event, he would be in a position to disrupt that region's oil production, and you would become progressively poorer and ever more vulnerable to his threats of death and destruction.
If you think fighting for oil is "evil," try living with a lot less oil for the many years it would take to exploit domestic oil sources (if environmentalists will let us) and to develop substitutes for it. If you think that leaving the Middle East to its own devices would buy "peace in our time," put the face of Adolf Hitler on Osama bin Laden. It's not hard to do, is it?
Perhaps this is all too much for you. Perhaps you would simply like to declare your independence from the policies of the United States and declare to the world that your person and possessions are off-limits to attack. Do you think al Qaida will go to the trouble of putting a tracking device on you and exempting you from harm when it blows up the building or airplane you happen to be in?
Oh, but you just want peace. Well, I want peace, too, but a peace that's on my terms, not the enemy's. Tell me your plan for achieving a peace that isn't the peace of the grave. Tell me how you would deal with the reality that we have a vicious enemy who would impoverish us if he cannot enslave us. Tell me how marching for peace, instead of killing the enemy, advances the cause of a peace that's worth having.