Bush, in his Sept. 11 speech, argued it is. But some experts say many Iraqi insurgents have local goals.
The war in Iraq constitutes a perimeter defense of the United States. Simply put, the US is fighting Al Qaeda and other extremists there, so it doesn't have to fight them on American soil.
That's the way President Bush sees the situation, anyway. In his speech to the nation on Sept. 11, he said that terrorists wouldn't quit fighting if the US pulled out of Iraq. Instead, they'd pursue their target, in essence pouring through a gap in US lines. "They will not leave us alone. They will follow us," said Mr. Bush. "The safety of America depends on the outcome of the battle in the streets of Baghdad."
Is that really the case? Many critics of the administration think Iraq is not the foremost trench in a global war on terrorism. The enemy there, they say, is only loosely related to the one that struck at the American heartland five years ago.
Most insurgents in Iraq are natives, not wandering members of a terrorist international. It's unlikely they'd look for further ways to target the US if it left, say some terrorism experts.
"It's like in the Vietnam era, when they said we'd be fighting communists in San Diego if we pulled out," says John Mueller, a professor of national-security studies at Ohio State University in Columbus. "It's a preposterous argument."
The White House has long argued that the war in Iraq needs to be judged as part of a larger historical context. And one lesson of 9/11, Bush said in his speech on the fifth anniversary of the attacks, is that the US must confront threats before they reach its shores.