Secretary of State Antony Blinken will meet Russian Foreign Minister Sergei Lavrov in Geneva on Friday in an effort to resolve the standoff over Ukraine, with U.S. officials warning that a Russian invasion could be imminent.

The meeting will follow a week of intense diplomacy as the top U.S. diplomat heads to Ukraine and Germany for discussions on the crisis, the State Department said. Adding urgency to Blinken’s talks is Russia’s fresh deployment of troops to Belarus to conduct major military exercises that will further strengthen the number of Russian forces along Ukraine’s border.

The troop movements, coupled with statements from Moscow that it was unsatisfied with meetings held with U.S., European and NATO officials last week to address its security concerns, have had some officials in Washington fearing the worst.

“We’re now at a stage where Russia could at any point launch an attack on Ukraine,” White House press secretary Jen Psaki said in a briefing with reporters Tuesday. The Biden administration has accused Moscow of sending operatives into Ukraine to prepare a “false flag operation” to use as a pretext for an invasion. Russia has denied the charge.

Despite the troubling developments, a senior State Department official said the meeting between Blinken and Lavrov in the Swiss city indicated that “diplomacy is not dead.”

“We are prepared to continue to engage with Russia on security issues in a meaningful, reciprocal dialogue,” said the official, who spoke to reporters in a phone briefing on the condition of anonymity under rules set by the department. “We will see this Friday if Russia is prepared to do the same.”

The official declined to say if the United States or Russia first proposed the meeting.

Russia has placed some 100,000 troops along the border with Ukraine alongside tanks and heavy weaponry. Russia has denied that it is preparing a military invasion but has said the West must take into account its security demands, which include the provision of legally binding assurances that Ukraine and Georgia will not become members of the NATO military alliance.

The Biden administration has refused to consider that demand, calling NATO’s “open door” policy sacrosanct despite widespread doubts that Ukraine will ever meet the military alliance’s criteria for membership.

U.S. officials are now left guessing if their decision to reject what Russia describes as its core demands will precede what some military analysts say could be the largest ground war in Europe in decades. Despite Washington’s vast spying apparatus, bolstered by satellites and surveillance planes, Russian President Vladimir Putin’s appetite for an invasion remains unknown.