Japan will not send warships to join a US-led maritime force to guard oil tankers in the Strait of Hormuz fearing a military response from Iran, but it may send patrol aircraft, said the Mainichi newspaper, citing unidentified government sources, Reuters reports.

But Japan may send warships independently to protect Japanese ships in the world’s most important oil artery, the newspaper said on Friday.

“We are closely monitoring the situation and continue to collect information while working closely with the United States and other countries,” said Japan’s Chief Cabinet Secretary Yoshihide Suga, when asked about the report.

As its key Asian ally and a major regional naval power, Washington is keen for Japan, which is the world’s fourth-biggest oil buyer, to play a major role in its proposed maritime force.

Press: South Korea to send naval unit to Strait of Hormuz

Japan’s government would likely face opposition at home to any military venture that could put its Self Defence Forces in harms way or threaten the well being of Japanese living in Iran. Japan’s military has not fought overseas since World War Two.

The United States has blamed Iran for a series of attacks since mid-May on shipping around the Strait of Hormuz, including one on a tanker operated by a Japanese shipping company. Tehran rejects the allegations.

US Secretary of State Mike Pompeo last week called on Japan, Britain, France, Germany, South Korea, Australia and other nations to join a maritime force to guard oil tankers sailing through the Strait of Hormuz.