Two Air Force cargo planes left South Korea for Hickam Air Force Base in Hawaii on Wednesday carrying 55 flag-draped crates that are thought to contain the remains of American troops lost during the Korean War.

The bones, which were turned over by the North Korean government after a meeting in June between Mr. Trump and the North Korean leader, Kim Jong-un, are bound for a forensic laboratory run by the Defense POW/MIA Accounting Agency in Honolulu, for testing that may finally offer answers to families that have been waiting for 65 years or more.

“I was a kid who would run to the phone and the mailbox every day, hoping there was some news about my dad — it never came,” said John Zimmerlee, 69, whose father was a navigator in a B-26 bomber that was shot down over Korea in 1952.

But if past efforts to identify remains returned by the secretive dictatorship are any indication, experts say, it will be no simple task to put names to any of the latest batch, and the job may never be entirely completed.