(Reuters) – U.S. President Donald Trump on Sunday threatened to restart war with Iran even as Vice President JD Vance met Iranian officials for the first talks under an interim peace ​deal, overshadowed by Tehran’s announcement it had again closed the Strait of Hormuz.

The talks in the Qatari-owned mountaintop resort of Buergenstock in Switzerland were the first to be held under the terms a memorandum of understanding agreed a week ago.

It calls for the strait to be reopened and a halt to all hostilities, including in Lebanon, which U.S. ally Israel invaded in March. But Iran, arguing that Washington had failed to meet its commitment to halt fighting in Lebanon, said it had shut the strait again and that Sunday’s talks would not cover substantive issues such as Iran’s nuclear programme.