The U.S. military is expecting the repatriation of U.S. service members’ remains from North Korea in coming days, officials said Wednesday, a sign of renewed cooperation between the two countries in the wake of President Trump’s summit with Kim Jong Un.

“United Nations Command Korea is planning for the repatriation of the remains of U.S. service members previously recovered by the Democratic People’s Republic of Korea,” said Col. Chad Carroll, a spokesman for U.S. forces in Korea. “We owe a profound debt of gratitude to U.S. service members who gave their lives in service to their country, and we are working diligently to bring them home.”

As part of Trump’s agreement to address North Korea’s nuclear program, the two nations committed to sending home the remains of U.S. soldiers, “including the immediate repatriation of those already identified.”

Officials said a transfer could occur in the next few days but that details and exact timing have not been finalized.

Trump, speaking at a rally in Minnesota on Wednesday, appeared to suggest the transfer had already occurred.

“We got back our great fallen heroes, the remains,” he said. “In fact, today, already 200 have been sent back.”

According to the Defense POW/MIA Accounting Agency, 7,700 American service members remain unaccounted for from the Korean War, and about 5,300 are believed to be located within North Korea.

North Korean officials have said they have the remains of about 200 U.S. service members that they have recovered since the active conflict with the United States ended in 1953.

CNN reported Tuesday that the remains of as many as 200 U.S. troops could be returned as part of that agreement, but officials said it was too early to say how many would be included.

Repatriation of remains has occurred in the past, but only sporadically because of tensions between the two countries.

The United States launched 33 investigative and recovery missions into North Korea between 1996 and 2005, but those efforts ended as the political situation between Washington and Pyongyang deteriorated.

In 2007, North Korea agreed to repatriate the remains of six soldiers as the George W. Bush administration made its own disarmament attempt. In 2012, the U.S. military announced that it was planning to launch another recovery mission with North Korean approval after three days of talks in Bangkok, but that effort also was scuttled.

The failed 2012 mission was expected to focus on two areas: Unsan County, about 60 miles north of Pyongyang, and the Chosin Reservoir. The latter was the site of fierce fighting, and the remains of more than 2,000 U.S. soldiers and Marines are believed to be missing there, U.S. military officials said at the time.

Looking forward to the expected transfer, officials said the multinational U.N. Command in South Korea, headed by an American four-star general, would probably receive the remains from North Korean authorities, possibly along the two countries’ border. Then, in South Korea, the Pentagon agency responsible for prisoners of war and missing troops would take custody of the remains.

They would then be taken to the United States, probably to Hawaii, for what could be a lengthy process of forensic analysis aimed at determining the service members’ identities so that families can be confirmed.

Even if the United States is able to begin recovering more remains from North Korea, many more years of work will be needed to identify many of the U.S. troops who died there, said Sarah E. Wagner, an anthropologist with George Washington University who has worked on military repatriation issues.

“This is not something that within a couple of months we will have 200 service members identified,” she said.I can guarantee that. It will take time. Already, so much time has passed, but to do it right, it is going to take a lot more.”

DNA analysis, mitochondrial testing and archival research of the deceased troops potentially involved all could play a role in the remains definitively being identified, Wagner said.

When the United States recovered 208 cases of remains from the North Koreans in the 1990s in what became known as the “K208 cases,” scientists found that they were extensively commingled, with the remains of at least 400 service members inside. That sort of “veritable jigsaw puzzle” could await researchers again now, Wagner said.

News of the expected transfer comes as U.S. officials look for signs that North Korea intends to follow through with its stated desire to denuclearize.

Speaking to reporters at the Pentagon on Wednesday, Defense Secretary Jim Mattis said he had not yet seen any steps by North Korea to dismantle its nuclear program.

“Obviously, it’s the very front end of a process,” he said. “The detailed negotiations have not begun. I wouldn’t expect that at this point.”

John Hudson in Washington and Philip Rucker in Duluth, Minn., contributed to this report.