Europe is facing its most significant security danger since the Cold War, EU foreign policy head Josep Borrell said Monday, while still hoping for a diplomatic solution to the Ukraine crisis.

When asked about the US predictions of an impending Russian invasion of Ukraine at a joint press conference with Secretary of State Antony Blinken in Washington, Borrell said they shared “a serious worry” about the situation on the ex-Soviet state’s frontiers.

“We are, in my opinion, living in the most hazardous period for European security since the end of the Cold War,” Borrell told reporters.

“Nobody packs 140,000 heavily armed soldiers on a country’s border without it constituting a severe threat,” he added.

“140,000 troops massed on the border is hardly a place to go for tea,” Borrell said.

According to US authorities, Moscow has gathered 110,000 troops along the Ukrainian border and is on pace to collect a strong enough force – perhaps 150,000 soldiers – for a full-scale invasion within weeks.

“This is not alarmism,” Blinken said, denying Washington’s attitude. “These are simply the facts.”

Should Russian President Vladimir Putin proceed with an invasion of neighboring Ukraine, both the United States and the European Union have threatened to strike with unprecedented economic penalties.

“We don’t believe Mr. President Putin has taken a choice, but he has put in place the capability, should he so choose, to strike very swiftly against Ukraine, and in ways that would have awful implications for Ukraine, for Russia, but also for all of us,” Blinken added.

Nonetheless, both Blinken and Borrell emphasized that diplomacy was still hard at work to end the situation peacefully.

“We feel that a diplomatic solution to the problem is still conceivable,” Borrell said. “We hope for the best, but we plan for the worse.”