WASHINGTON (Reuters) — All signs suggest Russia is on the brink of invading Ukraine, U.S. Secretary of State Antony Blinken said on Sunday, but still vowed that Washington would use every opportunity until the last minute to see if diplomacy would dissuade Moscow from going ahead.

Speaking on CNN’s “State of the Union,” Blinken maintained Washington’s position that the deterrent impact of sanctions would be lost if they are triggered before an invasion despite Ukrainian President Volodymyr Zelenskiy’s passionate plea on Saturday to unleash them.

“Everything we are seeing suggests that this is dead serious, that we are on the brink of an invasion. We will do everything we can to try to prevent it before it happens,” Blinken said, adding that the West was equally prepared if Moscow invades.

“Until the tanks are actually rolling, and the planes are flying, we will use every opportunity and every minute we have to see if diplomacy can still dissuade President (Vladimir) Putin from carrying this forward,” he said.

Blinken said his planned meeting with Russian Foreign Minister Sergei Lavrov was still set to proceed next week as long as Moscow did not go ahead with the invasion.

President Joe Biden was also prepared to engage with Putin “at any time, in any format if that can help prevent a war,” Blinken added.

The White House said Sunday that Biden was canceling a trip to Delaware and remaining in Washington.

NATO Secretary-General Jens Stoltenberg, who joined CBS’s “Face the Nation” on Sunday, said “Russia is preparing for an invasion of Ukraine,” pointing to Moscow’s troop buildup on the Ukrainian border and the continuation of military exercises in the region.

Western leaders have been warning of an imminent Russian invasion of Ukraine, estimating that more than 150,000 Russian troops have encircled the country.

Earlier, the Belarus defense minister said his country and Russia were extending military drills that were due to end on Sunday.

The decision to extend the drills was made because of military activity near the borders of Russia and Belarus and an escalation of the situation in the Donbass region of eastern Ukraine, the Belarusian defense ministry said in a statement.

Washington has been warning that Russia could use false claims about the conflict in Ukraine’s Donbass region, including reports of mass graves and allegations of chemical weapons production, to justify an invasion of the former Soviet republic.

Asked if the decision made him more concerned about an invasion, Blinken said: “Yes.”

“All of this along with the false flag operations we’ve seen unfold over the weekend tells us that the playbook that we laid out is moving forward,” he said.

U.S. Defense Secretary Lloyd Austin in an interview with broadcaster ABC warned about “enormous casualties” if Russia were to deploy the tanks, armored vehicles, artillery and rocket forces it has massed on the Ukraine border.

“You could see a significant amount of combat power move very quickly now to take Kyiv,” he said, and added: “If he employs that kind of combat power it will certainly create enormous casualties within a civilian population.”

The Hill and Reuters contributed to this report.