Russia sharply escalated its military campaign against Ukraine on Monday night, recognizing two pro-Russian breakaway regions in eastern Ukraine before ordering troops into the territory.
Moscow has long maintained that it has no soldiers on the ground in eastern Ukraine.
But NATO chief Jens Stoltenberg said on Tuesday that Russia has had forces inside the two regions – known as the Donetsk People’s Republic (DPR) and Luhansk People’s Republic (LPR) – since they declared themselves in 2014.
Stoltenberg criticized the troop movement as “a further invasion of a country that has already been conquered”.
Putin has yet to set a timetable for troops to move into the breakaway regions, but in a speech on Tuesday afternoon, Biden described the events now unfolding in Ukraine as “the beginning of a Russian invasion.”
“This is a flagrant violation of international law and requires a firm response from the international community,” Biden said, while unveiling a raft of new sanctions.
Ukrainian President Volodymyr Zelensky, in a national address on Tuesday, said he is still practicing diplomacy as a way out of the crisis. He said reservists would be called up for military training, but there would be no general mobilization of the armed forces.
“We desire peace and quiet, but if we remain calm today, we will disappear tomorrow,” Zelensky said.
The Ukrainian president also referred to Putin’s announcement that the Minsk Accords – designed to end the fighting in eastern Ukraine – were no longer valid, saying that Ukraine remained committed to seeking its sovereignty and integrity.
“Ukraine did not have a state tradition of its own,” he said, apparently referring to the questioning of the country’s right to exist as an independent state, referring to its eastern region as “ancient Russian lands.”
On Tuesday, the European Union imposed sanctions on 351 Russian lawmakers who voted to recognize the breakaway regions, and the United Kingdom announced imposing sanctions on five Russian banks and three Russian oligarchs.
The Baltic states – which have long feared an encirclement of Russia – watched Monday’s events with concern.
“Putin has just put (Franz) Kafka and (George) Orwell to their shame: no limits to the imagination of a dictator, no limits too low, no lies so blatant, no red lines that cannot be crossed,” the Prime Minister of Lithuania, Ingrida Simonetti, wrote on Twitter.
“What we witnessed tonight may seem surreal to a democratic world,” she said. “But the way we respond will define us for generations to come.”
Amid the uproar of countries condemning the planned Russian incursion, some countries have shied away from criticizing Moscow.
During an emergency meeting of the UN Security Council on Monday night, India called for “restraint on all sides”, stopping short of criticizing Russia.
“However, Kenya rejects such a yearning to be pursued by force. We must complete our recovery from the embers of dead empires in a way that does not return us to new forms of domination and oppression,” he said, adding that Kenya rejects “expansion on any grounds, including factors racial, ethnic, religious or cultural.”
For nearly eight years, the breakaway regions of Donetsk and Luhansk witnessed low-intensity conflict between Russian-backed separatists and Ukrainian forces, resulting in more than 14,000 deaths.
Kiev and the West maintain that the region is part of Ukrainian territory, although the Ukrainian government maintains that the two regions have, in fact, been under Russian occupation since 2014, when the conflict began in eastern Ukraine.
Correction: This story has been updated to correct the completion date for Nord Stream 2.
Anna Chernova, Vasco Kotovio, Joseph Attaman, Pierre Byrin, Ivana Kutsova, and CNN’s Helen Reagan contributed to this report.