Hegseth said the United States had successfully secured a path through the Strait of Hormuz and that hundreds of commercial ships were lining up to pass through as US forces seek to break a choke hold Iran has asserted on the waterway since the conflict began on February 28.
"We know the Iranians are embarrassed by this fact. They said they control the strait. They do not," Hegseth told a Pentagon news conference.
The US military says it sank six Iranian small boats and intercepted Iranian cruise missiles and drones after US President Donald Trump sent the navy to escort stranded tankers through the Strait of Hormuz in a campaign he called "Project Freedom".
Several merchant ships in the Gulf reported explosions or fires on Monday, and an oil port in the United Arab Emirates, which hosts a large US military base, was set ablaze by Iranian missiles.
General Dan Caine, the chairman of the Joint Chiefs of Staff, said that since the ceasefire was announced on April 7, Iran had fired at commercial vessels nine times and seized two container ships.
He said Iran has attacked US forces more than 10 times.
However, the attacks fell "below the threshold of restarting major combat operations at this point," Caine told reporters.
Asked whether the ceasefire with Iran still held, Hegseth said: "The ceasefire is not over."
"We said we would defend and defend aggressively, and we absolutely have. Iran knows that, and ultimately, the president can make a decision whether anything were to escalate into a violation of a ceasefire," he said.
The operation is Trump's latest effort to force an end to the disruption of international energy supplies caused by Iran's blockade of the strait, which carried a fifth of global oil and liquefied natural gas before the war.
The US navy is also enforcing a maritime blockade of Iran, which prevents ships from going to Iran or departing Iranian territory.
Shortly after Hegseth spoke on Tuesday, the UAE's defence ministry said its air defences were again dealing with missile and drone attacks coming from Iran.
The UAE foreign ministry said in a statement that the attacks were a serious escalation and posed a direct threat to the country's security, adding that it reserved its "full and legitimate right" to respond.
There was no immediate comment on that from Iran, although earlier its parliament Speaker Mohammad Baqer Qalibaf had said breaches of the ceasefire by the US and its allies endangered shipping through the strait, which also carries a large share of the world's fertiliser supplies.
"We know well that the continuation of the current situation is unbearable for the United States, while we have not even begun yet," he said in a social media post.
with AP
