WASHINGTON — The remains handed over by North Korea last week in 55 boxes are “consistent with being Americans,” based on an initial examination, although none has been positively identified, a U.S. scientist who has seen the remains said Thursday.

Although President Donald Trump has publicly thanked North Korean leader Kim Jong Un for fulfilling the promise he made at their June 12 Singapore summit to return American war remains, U.S. officials had cautioned that little was known about the remains and that they could not be quickly identified.

John Byrd, director of the Defense Department laboratory in Hawaii where the 55 cases arrived on Wednesday, cited several reasons for saying that at least some of the remains appear to be those of Americans missing from the Korean War.

Byrd was present when North Korean officials turned over the 55 boxes at Wonsan airport in North Korea last Friday, and he was among the U.S. government specialists who made a further preliminary examination of the contents after the boxes were flown to Osan air base in South Korea the same day.

A cursory examination at Wonsan confirmed that the remains were human, he said, and a closer look at Osan gave reason to believe they likely are Americans.

“What we saw were remains that were consistent with what we have found from the Korean War recoveries that we’ve done over the years, and we found remains that were consistent with being Americans,” Byrd said.

“We have remains that look to have been in a state of preservation consistent with coming from the Korean War era,” he said, and materials provided with the remains included U.S.-issued military equipment such as canteens and buttons. He said the remains are “good candidates to be missing Americans from the Korean War.”