The U.S. naval blockade of Iran is just an example of "polite" behavior during the ongoing ceasefire and U.S. forces are ready to strike Iran's power plants and energy industry if ordered, Pentagon chief Pete Hegseth said on Thursday.

Standing alongside two of the U.S. military's most senior officers, Hegseth said Iran needs to choose wisely as it prepares for negotiations with the United States.

"We are reloading with more power than ever before, and better intelligence," Hegseth said at a Pentagon news briefing. "We are locked and loaded on your critical dual-use infrastructure, on your remaining power generation, and on your energy industry. We'd rather not have to do it."

President Donald Trump's administration expressed optimism on Wednesday about reaching a deal to end the Iran war, while also warning of increasing economic pressure against Iran if it remains defiant.

That has included a blockade of Iran that went into effect on ‌Monday, with the U.S. military forcing 13 ships to turn around.

Trump is hoping the blockade will force Iran to accept U.S. terms ⁠for ending a war, which was launched by the United States and Israel on February 28, including opening up the Strait of Hormuz, a waterway through which roughly one fifth of global oil and gas exports ordinarily transits. Trump has said ​that was also a condition of the ceasefire due to expire next week.

Hegseth, in comments aimed at the Iranian leadership, said that the blockade "is the polite way that this can go."

General Dan ​Caine, chairman of the U.S. military's Joint Chiefs of Staff, said American forces are "ready to resume major combat operations at literally a moment's notice."

U.S. Navy ships would pursue any Iranian-flagged vessel or any vessel attempting to provide material support to Iran, ​Caine told the briefing.

Ships trying to break the blockade would be intercepted and warned that "if you do not comply with this blockade, we will use force," and enforcement would occur inside Iran's territorial seas and in international waters, Caine said.

No ships have been boarded so far, Caine said.

The U.S. military has widened its blockade to include cargoes deemed contraband, and any vessels suspected of trying to reach Iranian territory will be "subject to belligerent right to visit and search," the U.S. Navy said in an advisory on Thursday.

"These vessels, regardless of location, are subject to visit, board, search, and seizure," the Navy said in an updated advisory.

Contraband items listed included weapons, weapons systems, ammunition, nuclear materials, crude and refined oil products as well as iron, steel and aluminum.

-Reporting by Idrees Ali and Phil Stewart; writing by Phil Stewart and David Ljunggren; editing by Michelle Nichols and Will Dunham/Reuters