The government is avoiding taking sides in the dispute surrounding U.S. claims of Iranian involvement in Thursday’s attacks on two oil tankers, including one operated by a Japanese company, near the Strait of Hormuz.

In order not to harm Japan’s traditional friendly ties with Iran, the government is also reluctant to take up the incident when it chairs a Group of 20 summit in the city of Osaka on June 28 and 29, a government source said.

The United States has accused Iran of the tanker attacks, which occurred during a visit to Iran by Prime Minister Shinzo Abe, who was there to mediate between the two countries. Tehran has called Washington’s accusations groundless.

At a news conference Monday, Chief Cabinet Secretary Yoshihide Suga declined to answer a question about Tokyo’s view on the tanker attacks. “I refrain from answering with prejudice now,” Suga said.

A senior Foreign Ministry official described the country’s unique ties with Iran as a “diplomatic asset.”

“We can’t make any statement based on a presumption,” said the senior diplomat, adding that the U.S. government should disclose more information on the Hormuz incident.

Another government source referred to the Iraq war, which the United States initiated after intelligence analyses of Iraq falsely pointed to the country possessing weapons of mass destruction.

“We can’t unreservedly accept U.S. claims,” the source said.

A former Cabinet member of the ruling Liberal Democratic Party even suggested the possibility of a U.S. conspiracy behind the tanker attacks.

Meanwhile, some members of the government are waiting to see the results of a third-party investigation proposed by U.N. Secretary-General Antonio Guterres.

However, any such investigation would likely take time, leaving the government to maintain an ambiguous position on the matter, observers say.

The operator of the Japan-owned ship, the Kokuka Courageous, said Sunday in Dubai that the ship had arrived safely and had anchored off the coast of the United Arab Emirates with its crew all aboard.

Damage assessment on the Kokuka Courageous and preparation for ship-to-ship transfer of its cargo will start after authorities in Sharjah, one of the UAE’s seven emirates, complete security checks, Bernhard Schulte Shipmanagement said.

Thursday’s attacks, which also hit the Norwegian tanker Front Altair, have heightened tensions between Iran and the U.S. and its Gulf allies after similar blasts in May struck four ships, including two Saudi oil tankers, off the UAE.

The Front Altair is sitting off Sharjah’s Khorfakkan port, while the Kokuka Courageous is anchored off the emirate’s Kalba port, according to Refinitiv Eikon ship tracking data.

“Our crew remain on board the Kokuka Courageous. They are safe and well,” Bernhard Schulte said in a statement. It said there is no fixed schedule for the transfer of the methanol cargo.

The Kokuka Courageous’s 21 crew members were returned to the vessel by the U.S. Navy’s Bahrain-based Fifth Fleet after being rescued.