Japan's Prime Minister Shinzo Abe, who has tried to carve out a role mediating between Washington and Tehran, said Monday he was "deeply worried" by tensions in the Middle East.
The US assassination of Iranian military commander Qasem Soleimani last week has raised fears of an all-out conflict, with President Donald Trump threatening "major retaliation" if Tehran makes good on a pledge to avenge the killing.
"Middle Eastern tensions are increasing. I'm deeply worried about the current situation," Abe said in his first comments since the killing of Soleimani in Iraq.
"A further escalation in this situation should be avoided and I call for diplomatic efforts by parties concerned."