Ship traffic has picked up in the Strait of Hormuz since Iran and the U.S. signed an interim deal to end a war that constricted global oil supplies and fueled inflation, but questions surrounding control of the vital waterway and whether vessels will be charged tolls to cross it could interfere with negotiations to forge a lasting peace.

Tehran and Washington clashed over the Strait of Hormuz again this past weekend. Citing Israel's latest attacks on Lebanon, Iran declared that it reclosed the strait. The U.S. was quick to contest that. Maritime tracking data showed that dozens of ships passed through on Saturday and Sunday, though far fewer than the daily average before the war.

U.S. Secretary of State Marco Rubio will travel to the United Arab Emirates, Kuwait and Bahrain this week as the Trump administration has stepped up efforts to end the war with Iran while Gulf countries remain uneasy about a proposed deal.

The State Department announced Monday that Rubio would visit the three countries for bilateral meetings with leaders to discuss the memorandum of understanding reached last week between the U.S. and Iran, weekend talks in Switzerland between senior Iranian and U.S. officials as well as security for American allies and partners in the Middle East, including the status of the Strait of Hormuz.

Technical talks between Iran and the United States in Switzerland have concluded, with negotiating groups to be set up on nuclear issues and sanctions, Iran's state media reported Tuesday.

The negotiators "decided that four working groups would be established: Sanctions Termination, Nuclear Affairs, Reconstruction and Economic Development, and Monitoring and Implementation," said IRNA state news agency, quoting Deputy Foreign Minister Kazem Gharibabadi.

U.S. Vice President JD Vance said Monday that a first round of U.S.-Iran talks in Switzerland had laid a good foundation for reaching a final deal on ending the Middle East war.

"We laid a very good foundation for a successful final deal," Vance told reporters at the Burgenstock resort in central Switzerland, following negotiations that started on Sunday and went on into the night.

An explosion tore through Qatar's key natural gas export terminal Sunday night as workers tried to resume operations there after Iran bombed it during the war, causing a fire that hurt at least 54 people as another 18 were still missing hours later.

The blast at the Ras Laffan industrial area could cause further chaos in global energy markets, particularly as Qatar remains one of the world's top natural gas producers. Qatar shut down its production after Iran's chokehold on the Strait of Hormuz meant it couldn't get shipments out to its clients.

Iranian state television reported on Sunday a pause in the U.S.-Iran talks mediated by Pakistan and Qatar in Switzerland, and said that the Islamic republic's nuclear program had not been discussed.

"No negotiations regarding Iran's nuclear program took place during the 80-minute first round of talks," the state broadcaster said, adding that the focus had been on the implementation of the memorandum of understanding between Tehran and Washington, and the situation in Lebanon.

Iran's chief negotiator Mohammad Bagher Ghalibaf on Sunday warned the United States against making threats at the Islamic republic, vowing that "our armed forces are ready to respond".

U.S. President Donald Trump said Sunday in a surprising statement that "Iran must immediately stop their highly paid PROXIES in Lebanon from causing trouble," apparently referring to Iran-backed Hezbollah.

Iran said on Sunday that the ongoing conflict in Lebanon between Israel and Hezbollah will top the agenda in talks with the United States in Switzerland, as well as issues such as frozen Iranian funds and the sale of the country's oil.

U.S. President Donald Trump warned that the United States could impose tolls on the vital Strait of Hormuz waterway if negotiators are unable to complete a deal to end the war in Iran.

There will be no tolls "unless they are imposed by and for the United States of America, should the deal not be completed, for services rendered as the Guardian Angel to the countries of the Middle East for purposes of both past, present, and future reimbursement of costs," Trump posted on Truth Social.