Negotiations to end the war are at an impasse over Iran’s nuclear program and the Strait of Hormuz, which remains mostly shut.
Iran’s foreign minister has already arrived in the country, state media reported. He was believed to be carrying a written response to a U.S. proposal to end the war.
The killing of Ayatollah Ali Khamenei ushered in a new form of collective leadership in the country, with more power for the Revolutionary Guards.
A British naval agency said the two vessels had come under attack near the strait, as a U.S. blockade on Iran’s ports continued.
With the cease-fire on the verge of ending, President Trump said on Tuesday that he would keep it in place until Iran’s “proposal is submitted, and discussions are concluded, one way or the other.”
The delay is another hurdle in the Trump administration’s push to secure an agreement that would curb Iran’s nuclear program.
President Trump attributed his decision to divisions among the Iranians about how to proceed and said he wanted to give them more time.
Publicly, Iranian officials refuse to confirm a second round of negotiations with the United States, even as they privately say they are making plans to attend.
With the two-week cease-fire almost over, Vice President JD Vance was expected to head to Pakistan on Tuesday for the second round of negotiations.
The vice president is again center stage, after abruptly leaving the first round of high-level Iranian peace talks without an agreement.