The United States is planning to create a military coalition to safeguard commercial shipping from Iranian threats in waterways off Iran and Yemen following attacks on two oil tanker last month, U.S. media reported Tuesday.

"We are engaging now with a number of countries to see if we can put together a coalition that would ensure freedom of navigation both in the Strait of Hormuz and the Bab el Mandeb," said Marine Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff, to reporters.

Dunford also said he had discussed the plan with Mark Esper, the acting secretary of defense, and Secretary of State Mike Pompeo. He added the Pentagon has developed a specific plan and it would be clear within a couple of weeks to see which nations join the coalition, according to the local media.

Under the plan, the United States would provide command ships and lead surveillance efforts while its allies would patrol waters near the U.S. command ships and escort commercial vessels with their nation's flags, the reports said.

Dunford called the coalition "scalable," suggesting that it will start small but will expand as more countries show interest.

President Donald Trump expressed frustration in June, questioning why the United States is protecting shipping lanes for oil-dependent countries like China and Japan, suggesting that countries should be protecting their own ships.

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Bilateral tensions have increased with the United States stepping up its pressure on Iran over Tehran's nuclear program, claiming that it is destabilizing the Middle East.

Washington has blamed Tehran on the June attacks on two oil tankers respectively operated by a Japanese company and chartered by a Taiwanese oil refiner near the Strait of Hormuz, a key corridor through which major oil exports flow to the world, as well as a similar tanker attack in May in waters off the United Arab Emirates.

A U.S. drone was also shot down in Iran by the Middle Eastern country's paramilitary Islamic Revolutionary Guard Corps in late June, drawing the ire of Trump.

Iran has threatened in the past that it would close the Strait of Hormuz, further increasing tensions with the United States and some of its neighbors.

The United States and Gulf allies also have concerns about the vulnerability of the Bab el Mandeb, a strait between the Horn of Africa and Yemen, caused by Houthi rebels who are accused by the United States of being Iranian proxies.

In Tokyo on Wednesday at a regular press conference, Japan's Deputy Chief Cabinet Secretary Kotaro Nogami declined to comment on the U.S. media reports or whether Japan will join the coalition.

Describing the safety of navigation in the Strait of Hormuz as being "vital to our nation's energy security," Nogami only said that Japan will continue working with the United States and other nations to reduce tensions in the Middle East.

Defense Minister Takeshi Iwaya has so far expressed a negative view about dispatching Japan's Self-Defense Forces to the Strait of Hormuz, saying there were no more attacks on Japanese tankers.

The SDF has been escorting commercial vessels in the Gulf of Aden under an antipiracy operation since 2009.