By Phil Stewart and David Alexander
WASHINGTON (Reuters) - President Barack Obama pledged on Monday to forge ahead with his Afghan war strategy and the Pentagon sought to dispel fears of a Taliban resurgence after militants shot down a helicopter killing 30 U.S. troops, mainly elite Navy SEALs.
Saturday's crash was the deadliest incident for U.S. forces since the war in Afghanistan began nearly a decade ago and followed a series of high-profile assassinations and attacks by the insurgents over the past several months.
The incidents have raised concerns about the extent of U.S. progress in the decade-long conflict, but Obama and Defense Secretary Leon Panetta both said they were unwavering in their commitment to move ahead with the mission.
"We will press on and we will succeed," Obama said in a televised tribute to the dead. "Our troops will continue the hard work of transitioning to a stronger Afghan government and ensuring that Afghanistan is not a safe haven for terrorists."
Panetta, at a change of command ceremony at Special Operations Command in Florida, said the killings were a "reminder to the American people that we remain a nation at war" and promised to honor the dead by "showing the world our unyielding determination to press ahead."
"As heavy a loss as this was, it would even be more tragic if we allowed it to derail this country from our efforts to defeat al Qaeda and deny them a safe haven in Afghanistan," the defense secretary said.
U.S. military officials have repeatedly played down high-profile Taliban assassinations and attacks as an attempt by the militants to project an appearance of strength after a series of battlefield defeats that saw their former strongholds taken over by NATO forces.
"This one single incident does not represent any kind of watershed or trend," said Pentagon spokesman Colonel Dave Lapan. "We still have the Taliban on the run, we've reversed the momentum that they had. But they are still going to inflict casualties. That's what they do."
ELITE UNIT HIT
But the killing of so many Americans has resonated in a way at home that other battlefield incidents have not, with relatives, pastors and friends of fallen U.S. forces appearing in U.S. media, praising troops fighting an unpopular war that usually takes a backseat to concerns like the economy.
Many of the victims were from SEALTeam Six, the celebrated elite unit that carried out the covert raid in May to kill Osama bin Laden. U.S. officials have said none of the dead participated in the bin Laden raid.
"(My husband) felt, and so did the other members of his team, that the very existence of our republic is at stake," said Kimberly Vaughn, widow of Aaron Vaughn, a SEAL Team Six member, speaking on NBC television.
With the bodies expected to return to the United States on Tuesday, there has been speculation top officials might go to Dover Air Force Base to pay tribute to the service members.
Obama visited the base in October 2009 to pay his respects to 15 returning soldiers and three drug enforcement agents killed in Afghanistan.
The Pentagon said news media would not be allowed to cover the arrival ceremony because the remains have yet to be identified and therefore families would be unable to give their consent.
"If there were any -- any -- identifiable remains in this group -- five of them, three of them, one of them -- and the family said 'yes,' there would be coverage," Lapan said.
"We're only in this position because there are no identifiable remains."
The NATO-led International Security Assistance Force in Afghanistan said the CH-47 Chinook helicopter appeared to have been hit by a rocket-propelled grenade. Lapan told reporters the insurgents were presumed to be Taliban.
Critics of Obama's plan to withdraw 33,000 U.S. forces from Afghanistan by the end of next summer alternately attack the president for pulling out too slowly or too quickly from the war.
"We're going to have to address the problem that the President has created," said Senator John McCain, who lost to Obama in the 2008 election and wanted a slower pullout.
"There's the perception in Afghanistan and other parts of that part the world that America is withdrawing. That can't be good," he said on NBC's "Meet the Press" on Sunday.
(Additional reporting by Laura MacInnis in Washington and Paul Tait and Michelle Nichols in Kabul; Editing by Philip Barbara and Todd Eastham)