WASHINGTON, D.C. -- Safely back from a surprise visit to Afghanistan, President Barack Obama is taking fire here for using the decade-long war and the death of Osama bin Laden as props in his re-election campaign.

One year ago, Obama ordered U.S. Navy SEALs to storm bin Laden's compound in Pakistan and kill the world's most hunted man and mastermind of the 9/11 terrorist attacks.

Last week, his re-election campaign aired a new television ad hailing his decision to go after bin Laden and raising doubts about whether Mitt Romney, the presumptive Republican nominee, would have done the same.

His critics say that went too far.

Romney himself, who has praised the president for ordering the raid that killed bin Laden, said it was "inappropriate" to use the event for political gain.

"I think politicizing it and trying to draw a distinction between himself and myself was an inappropriate use of the very important event that brought America together," Romney said this week.

And a grassroots political advocacy group, Veterans for a Strong America, unveiled a new web ad Wednesday criticizing Obama for capitalizing on the successes of the armed forces.

"Heroes don't seek credit. Heroes don't spike the football," banners read in the ad. "Our service members sacrifice to protect our country, not to benefit his (Obama's) political campaign."

But conservatives were quick to praise Obama for his secretive trip to the war zone to sign a new agreement with President Hamid Karzai spelling out the U.S. withdrawal from the war and pledging an ongoing relationship with the war-torn country until 2024.

"Our troops and the American people deserve to hear from our president about what is at stake in this war," Romney said about Obama's trip, which lasted less than eight hours and was convened in the cover of darkness.

And Sen. John McCain told CNN it's "always good when the president goes to where our young men and women are in harm's way."

Others, though, like Republican Sen. James Inhofe, blasted Obama's trip as nothing more than a campaign stop.

"This trip to Afghanistan is an attempt to shore up his national security credentials, because he has spent the past three years gutting our military," Inhofe said in a statement late Tuesday. "He cut the F-22, future combat system, C-17 and our ground-based interceptor in Poland, to name a few. On top of that, he has tried to close Gitmo, the very source of some of our intelligence that resulted in bin Laden's demise."