Iran’s supreme leader sent his foreign minister to Moscow on Monday to ask President Vladimir Putin for more help from Russia after the biggest US military action against the Islamic Republic since the 1979 revolution over the weekend.

US President Donald Trump and Israel have publicly speculated about killing Supreme Leader Ayatollah Ali Khamenei and about regime change, a step Russia fears could sink the Middle East into the abyss.

While Putin has condemned the Israeli strikes, he has yet to comment on the US attacks on Iranian nuclear sites though he last week called for calm and offered Moscow’s services as a mediator over the nuclear programme.

A senior source told Reuters that Iranian Foreign Minister Abbas Araghchi was due to deliver a letter from Khamenei to Putin, seeking the latter’s support.

Iran has not been impressed with Russia’s support so far, Iranian sources told Reuters, and the country wants Putin to do more to back it against Israel and the United States. The sources did not elaborate on what assistance Tehran wanted.

But Putin, whose army is fighting a major war of attrition in Ukraine for the fourth year, has so far shown little appetite in public for diving into a confrontation with the United States over Iran just as Trump seeks to repair ties with Moscow.