Which nation did the United States invade as a part of its counterterrorism efforts?

A. Iraq

B. Iran

C. Pakistan

D. Afghanistan

The answer to this question is: D. Afghanistan.

The United States invasion of Afghanistan occurred after the September 11 attacks in late 2001, supported by close allies. The conflict is also known as the U. S. war in Afghanistan.

"The Bush administration also stated the Iraq war was part of the War on counter-terrorism efforts."

So the correct answer is A) Iraq