North Korea announced an agreement Friday to discuss how the U.S. could recover remains of American troops killed in the Korean War, the most significant sign of progress since U.S. officials halted such work in 2005.

Roughly 8,000 U.S. service members remain missing, with 5,500 of them thought to be buried in North Korea, according to the Pentagon.

The North’s state media, Korean Central News Agency, quoted an unnamed foreign ministry official Friday saying that Pyongyang had accepted the U.S. proposal to talk and that preparations for discussion had begun.

Relatives of the missing soldiers reacted to the news with hope.

“The void that was created all those years ago never gets filled,” said Rick Downes, 63, whose father’s plane went down in North Korea when Downes was 3 years old. For decades, relatives like him have followed the ups and downs of North Korea’s turbulent diplomacy, with the chances of recovering their loved ones changing with each development.

“There’s some bitterness there,” said Downes, president of the Coalition of Families of Korean and Cold War POW/MIAs, “because of how people over time have politicized this as an issue.”

In 1996, after negotiations, the U.S. military began excavations in North Korea to search for missing U.S. service members. Over nearly a decade, such operations yielded 229 sets of remains, according to the Pentagon’s Defense Prisoner of War/Missing Personnel Office.

But of that number, only 87 have been identified and returned to families. Part of the problem was that many remains uncovered by North Korean workers were jumbled together, and the U.S. office struggled to sort them out.

Then in 2005, the United States stopped its recovery operations amid rising tension with the North over its unwillingness to disarm its nuclear capabilities. The six years of diplomatic gridlock since then have frustrated many family members.

Now, after a particularly low period in the relationship between North and South Korea — including a torpedo attack attributed to the North that sank a South Korean warship, killing 46 sailors; the shelling of a South Korean island by the North, which killed four; and the North’s detonation of a nuclear weapon in a test — both parties seem headed into an upswing.

In recent weeks, North Korea has ramped up its dialogue with the South and with the United States. Nuclear envoys from the North and South met this summer after several largely silent years. Officials from the North also met with U.S. leaders in New York last month.

And Thursday, just hours before North Korea’s agreement to talk about recovering remains, the United States pledged $900,000 in flood aid to the North.

But Washington has been careful in calibrating its reengagement with Pyongyang, declining to resume broader multinational talks on the North’s nuclear disarmament without some sign of commitment.