President Barack Obama made a Memorial Day call to Americans Monday not to forget their countrymen still fighting in Afghanistan even as the United States winds down its long war there.

In a somber speech at Arlington National Cemetery, Obama evoked by name some of those recently buried at the military cemetery -- a young Black Hawk helicopter pilot, a humble combat medic, a Marine remembered for bringing his troops home safely.

"Fewer Americans are making the ultimate sacrifice in Afghanistan and that is progress for which I am profoundly grateful. This time next year we will mark the final Memorial Day of our war in Afghanistan," Obama said.

"But even as we turn a page on a decade of conflict, even as we look forward, let us never forget as we gather here today that our nation is still at war," he said.

Nearly 12 years after the September 11, 2001 attacks that launched the United States into its longest war, about 66,000 US troops are still deployed in Afghanistan.

Obama has said that 34,000 will come home this year, and most of the remainder by the end of 2014, although a small residual force is expected to stay behind to train and support Afghan security forces.

The US death toll has climbed to 2,228 -- about half the number of US service members killed in Iraq, according to the website icasualties.com, which tracks those statistics.

In his speech, Obama touched on the growing gulf in American society between the relatively small number of Americans who have borne the brunt of the conflict and the larger civilian population.

A professional, all-volunteer force and huge advances in technology have meant that US wars are now fought and suffered by narrow sectors of society, out of public view.

"Regardless of the reason the truth cannot be ignored today that most Americans are not directly touched by war," Obama said.

"And the consequence is not all Americans may see or fully grasp the depth of sacrifice, the profound costs that are made in our name, right now, every day, as we speak," he said.