US Secretary of State Antony Blinken said he would speak to Russian counterpart Sergei Lavrov Saturday in a last-ditch attempt to head off a possible invasion of Ukraine.

“We continue to see very troubling signs of Russian escalation, including new forces arriving around Ukraine’s borders,” Blinken said in a press conference in Fiji.

“If Russia is genuinely interested in resolving this crisis of its own making through diplomacy and dialogue, we’re prepared to do that,” he said.

“But it must take place in the context of de-escalation. So far, we’ve only seen escalation from Moscow,” he said.

“This is a pivotal moment. We’re prepared for whatever should happen,” he said.

The top US diplomat reiterated that Washington and its allies will “swiftly” impose punishing sanctions on Russia if it invades Ukraine, which he said could now start “at any time”.

“We don’t know whether President Putin has made that decision,” he said.

“But we do know that he has put in place the capacity to act on very short notice.