July 13 (UPI) — President Donald Trump said Monday that the United States would be “taking over the strait” after days of the United States and Iran trading attacks amid a fragile cease-fire.

The United States is reimplementing its blockade of the Strait of Hormuz, targeting all ships using Iranian ports. The return of unease over the strait, a key passage in the oil trade for the Middle East market, has caused oil prices to climb once again.

After Trump’s announcement of resuming the blockade, the price of Brent crude oil, the international benchmark, increased by 7.1% to $81.40 per barrel on Monday morning. West Texas intermediate, the U.S. benchmark, increased by 7.2% to $76.50.

The president has notified Congress that military action against Iran has resumed, calling it “limited, measured, planned, and executed in a manner designed to minimize civilian casualties.”

Trump said that in addition to managing the Strait of Hormuz, the United States should be reimbursed for its efforts. He made the comments during a phone interview with Fox + Friends.

“We are taking over the strait. They have nothing. They’ve got nothing,” he said of Iran.

“We’re going to keep the strait, and we’ll probably run it. We’ll become the guardian of the strait. Maybe we’ll call it the guardian angel of the strait.”

Trump said the United States should be reimbursed for controlling the strait “because the other nations are very wealthy.”

“They’re on our side, and we can’t be expected to do that for nothing,” he added, suggesting that the United States could charge ships for passage through the strait.

Iran’s military responded, saying it won’t allow the United States to control the waterway, through which one-fifth of the world’s oil supply travels, the BBC and The Guardian reported. A statement from the military said the United States’ “frequent misadventures” have “seriously jeopardized the security of the region.”

“If the war expands in the region, the flames of war will engulf all countries in the region,” the statement said.

Fears of an expanding war have spread in recent days as the United States and Iran traded attacks amid renewed talks over an agreement to end the war. The two countries have a cease-fire in place under a memorandum of understanding despite a second-consecutive night of U.S. attacks Sunday and continued Iranian attacks on U.S. military assets in the region.

The Iranian Embassy in Britain released a statement Monday accusing the United States of violating the MOU “since day one” by “pushing vessels toward a dangerous southern parallel route” through the strait.

“That route is not only legally questionable but also unsafe, unreliable and prone to accidents,” the statement read. “Adding to the threat, U.S. military aggression, including attacks on Iran’s port & tower infrastructure, has turned the Strait of Hormuz into a tense, high-risk zone for maritime traffic.”

U.S. Central Command said Sunday that it hit dozens of Iranian targets with precision munitions with the aim of degrading Tehran’s “ability to continue attacking shipping flowing through the Strait of Hormuz. The attacks targeted air-defense systems, coastal radar sites, missile and drone capabilities, and small boats.