US President Donald Trump spoke Monday with Russian counterpart Vladimir Putin and pledged Washington's "full support" for Moscow's response to the deadly attack on the Saint Petersburg metro, the White House said.

Trump expressed his condolences and  condemned the attack, which killed 11 people and left dozens wounded. Russian authorities said they were probing an "act of terror."

"Both President Trump and President Putin agreed that terrorism must be decisively and quickly defeated," the White House statement said.