Iran declared the Strait of Hormuz closed again on Saturday and warned vessels to stay away from the critical shipping route, but the U.S. denied those claims, stating the waterway remained open.

Tensions between the two countries escalated just days after Tehran and Washington reached an interim agreement to end hostilities in the region.

The announcement by Iran’s military and the country’s Islamic Revolutionary Guard Corps came as Iranian negotiators prepared to travel to Switzerland for technical-level talks with U.S. officials scheduled to begin Sunday.

Iran’s joint military command said the closure of the strait was in response to continued Israeli military operations in Lebanon and what it described as U.S. “bad faith” and a failure to uphold commitments under the truce framework, AP reported. Iranian state television said “subsequent steps have been planned” if what it called aggression continues, according to multiple outlets.

Earlier Saturday, Israeli strikes in southern Lebanon killed at least 16 people, including two children, AP reported, citing Lebanese authorities. Lebanon’s state-run National News Agency said seven people remained trapped beneath rubble in Nabatiyeh and nearby villages following the attacks, according to AP.

The U.S. military said the Strait of Hormuz had not been closed, however, and said that ⁠U.S. forces ‌were monitoring the ⁠situation to ensure that it remained open, Reuters reported.

“Iran does not control the Strait ‌of Hormuz,” U.S. Central Command spokesperson Navy Captain ​Tim Hawkins told Reuters. “Traffic continues to flow, and U.S. forces ⁠are monitoring the situation to ensure ‌this remains the ‌case.”

The attempt to shut down the strait again raises the stakes ahead of the talks in Switzerland, which are intended to advance the interim agreement reached Wednesday between U.S. President Donald Trump and Iranian President Masoud Pezeshkian after nearly four months of war.

The signed memorandum of understanding had called for the immediate end to military actions by Israel in Lebanon and the full reopening of the Hormuz strait without tolls imposed by Iran for at least 60 days.

U.S. officials disputed Iran’s assertion that it had closed the Strait of Hormuz, Reuters reported.

“Iran does not control the Strait of Hormuz,” U.S. Central Command spokesman Navy Captain Tim Hawkins told Reuters. “Traffic continues to flow, and U.S. forces are monitoring the situation to ensure this remains the case.”

Vance says talks to continue

U.S. Vice President JD Vance struck an optimistic tone Saturday, saying negotiations were advancing despite Iran’s latest threat to shut the strait.

Speaking on Fox News earlier Saturday, Vance said Jared Kushner, Trump’s son-in-law, and special envoy Steve Witkoff in Switzerland were working through the agreement’s technical details. He added that discussions were “going well.”

Vance noted that tanker traffic had rebounded sharply following the ceasefire agreement.

“We actually got 16 million barrels of oil out of the Strait of Hormuz yesterday,” Vance said. “That is a record going back to even before the conflict started.”

He also said negotiators were focused on securing Iran’s enriched uranium stockpile to make it “effectively impossible” for Tehran to rebuild its nuclear program, while emphasizing that the United States retained significant economic leverage if Iran failed to comply with the agreement.

Vance said he expects to travel to Switzerland within days to join the Iran negotiations, though he cautioned that diplomatic arrangements involving Qatari and Pakistani mediators were still being finalized.