US President Donald Trump mourned the deaths of 13 US military service members in the war with Iran during a Memorial Day remembrance on Monday.

“These incredible men and women gave their lives to ensure that the world’s number one state sponsor of terror will never have a nuclear weapon," Trump said after laying a wreath at the Tomb of the Unknown Soldier.

“Oh, and they won’t. They will never have a nuclear weapon. I’m sure you know that one."

“In two wars recently, we’ve lost a total of 13 service members," he said.

“In Venezuela, which was a complete and total victory … we took that over in one day, lost no one. In Operation Epic Fury, we lost 13 wonderful souls - wonderful, special people," added Trump.

Trump announced on Saturday that the final details of an impending agreement with Iran would be announced "shortly."

Reuters reported that the plan would include three stages: the official end of the war, resolving the crisis in the Strait of Hormuz, and opening a 30-day window for negotiations on a broader agreement, with the option to extend the window.

Later, the New York Times reported that the core framework of a potential agreement between Washington and Tehran hinges on a major concession regarding the Islamic Republic's nuclear capabilities.

According to two US officials quoted in the report, the emerging deal requires Iran to completely forfeit its dangerous stockpile of highly enriched uranium, which Iran has committed to.

On Sunday, US officials stated that the formal completion of the memorandum of understanding between Washington and Iran could be delayed by several days.

According to a senior United States official quoted by CNN, the delay stems from a protracted and bureaucratic approval process required to obtain Tehran's official endorsement on the specific phrasing of the pact.