DOVER AIR FORCE BASE, Del. — Forced into the grimmest role of his job, President Barack Obama today prepared to privately honor the remains of fallen returning home from war, this time the troops killed in a helicopter attack that claimed more American lives than any other incident of the Afghanistan war.

Obama arrived at Dover Air Force Base to preside as the remains of U.S. forces were carried off a military cargo plane in flag-covered cases. His unscheduled afternoon trip here was kept secret to ensure the security of his helicopter flight to Delaware. Members of the media covering the trip agreed in advance not to report on it until he had landed.

An entrenched wartime president, Obama has been here before.

In the dark of an October morning in 2009, Obama watched solemnly as 18 Americans killed in the Afghan war came home, a visceral reminder of a war that has long slipped from the forefront of American debate. He would later call it the most powerful moment of his young presidency.

Obama is now honoring the U.S. forces killed in Afghanistan Saturday when their helicopter was shot down by a Taliban insurgent using a rocket-propelled grenade.

A total of 30 U.S. troops, seven Afghan commandos and an Afghan interpreter died.

They had been packed into a twin-rotor chopper, en route to help coalition ground forces in a battle with insurgents. Many of the Americans who died were members of the Navy’s SEAL Team Six, the elite unit that killed al-Qaida leader Osama bin Laden in a raid in Pakistan three months ago. None of the SEALs killed in the crash took part in the bin Laden mission.

The devastating loss comes just ahead of the 10th anniversary of the Sept. 11, 2001 attacks on America that prompted the war in Afghanistan.

Some of those killed had been motivated to join the Special Forces by the 9/11 attacks that bin Laden masterminded.

Two C-17 aircraft carrying the remains of 30 killed in a weekend helicopter crash arrived at the air base east of Washington.

Three days after the downing of the aircraft by insurgents, the Defense Department has not released the troops’ names. Officials said it is taking time because there were so many killed. Others said privately there is hesitancy to release the names because the majority were from secretive special operations forces.

But the stories of the fallen have been emerging in the days since the crash. Those killed included young fathers, accomplished athletes and people of deep faith. One had dreams of becoming an astronaut after military service. All were deeply committed to the cause.

To Americans focused on economic crises at home, the death toll is a reminder that tens of thousands of U.S. forces will be in harm’s way in Afghanistan through at least 2014.

Obama‘s other trip to Dover left searing images of a president standing in salute on a cold tarmac in the dead of night. One family had allowed media coverage.

In this case, reporters won’t see what Obama does.

The Pentagon ruled there will be no media coverage at the Dover base because the badly damaged remains from the horrific crash are mingled and still being identified.

“We will press on, and we will succeed,” Obama said Monday in his first public comments about the helicopter crash. “But now is also a time to reflect on those we lost and the sacrifices of all who serve, as well as their families. These men and women put their lives on the line for the values that bind us together as a nation.”

Obama scrambled his schedule to be at Dover when the bodies returned home. He canceled an event in Virginia.

The military calls the process of moving the remains a “dignified transfer.” Cases draped in American flags are carried off a giant plane, one by one, by a team of military personnel from the fallen member’s respective service. Each case is placed in a vehicle and then taken to a mortuary.

Top civilian and uniformed leaders will attend the proceeding, and so will some family members.