Defense Minister Takeshi Iwaya said Tuesday he has “no plan” to send the Self-Defense Forces to the Middle East to join a military coalition envisioned by the United States to safeguard commercial shipping from Iranian threats in the region.

The U.S. plan follows attacks on two oil tankers near the Strait of Hormuz last month, with one of them operated by a Japanese shipping firm. Iwaya said there have been no more similar attacks and that threats against Japan in the area are deemed to be “in a temporary lull at present.”

Due to restrictions by its pacifist Constitution, the hurdle remains high for Japan to send forces to the region.

The Strait of Hormuz is a key corridor through which major oil exports flow to the world.

The minister declined to comment on whether Washington has sounded Tokyo out about the coalition plan.

“We have been regularly communicating closely with the U.S. side, but we should refrain from divulging specific exchanges,” Iwaya said at a news conference.

He underlined the importance of continuing diplomatic efforts to ease tensions in the Middle East, where U.S. forces were on the verge of taking military action against Iran following the downing of an unmanned American drone by the country’s paramilitary Islamic Revolutionary Guard in late June.

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

Tensions between Washington and Tehran have increased, with the United States stepping up its pressure on Iran over the Middle Eastern country’s nuclear program and claiming that it could destabilize the region.