Russian forces invaded Ukraine overnight on President Vladimir Putin’s orders and attacked targets across the country, with Ukraine’s military responding.
The incursion was first announced from the air, with sirens heard in the capital, Kyiv. Ukraine later released footage of Russian military vehicles entering the territory and said the Russians had successfully captured Chernobyl, the extremely sensitive site of a deadly nuclear disaster in 1986.
Zelenskyy said the country was severing all diplomatic ties with Russia. He also vowed to give weapons to anyone who wants to defend Ukraine, and urged people to donate blood to help the effort.
Putin announced the invasion in a speech broadcast Thursday morning local time.
Putin had previously said that eastern regions of Ukraine controlled by Russian-backed separatists should be treated as independent and approved a military deployment into the country in what U.S. officials called an invasion.
President Joe Biden said in a statement that Moscow had launched an “unprovoked and unjustified attack.” Biden added late Wednesday that he would soon make an address on the situation and unveil new U.S. punishments for Putin on top of the financial sanctions he had announced in coordination with American allies earlier in the week.
“President Putin has chosen a premeditated war that will bring a catastrophic loss of life and human suffering. Russia alone is responsible for the death and destruction this attack will bring... the world will hold Russia accountable,” Biden said. “Tonight, Jill and I are praying for the brave and proud people of Ukraine.”
Russia’s Defense Ministry claimed it had targeted Ukraine’s airbases and rendered them and other military infrastructure “inoperable,” saying the country’s air defense systems had been “suppressed.” Ukrainian officials also said Belarus, a close ally of Putin, had deployed its own military as part of the assault on border checkpoints.
Some U.S. officials have called for Belarus to be part of any sanctions package that will be announced by the White House later Thursday.
Many Ukrainians began to flee major city centers after the incursion began. Major backlogs at gas stations filled streets with cars waiting to buy fuel. Others took refuge in the city’s subway tunnels as air sirens sounded across the city.
World leaders vowed to hold Russia accountable for the attack. French President Emmanuel Macron, who has been part of a last-ditch diplomatic effort, said his country “firmly condemned” Russia’s moves.
NATO Secretary-General Jen Stoltenberg said the attack put countless civilian lives at risk:
“Once again, despite our repeated warnings and tireless efforts to engage in diplomacy, Russia has chosen the path of aggression against a sovereign and independent country,” Stoltenberg said in a statement.
Zelenskyy, who has declared martial law, asked citizens to stay calm and said Ukraine remained “ready for everything.”
“We will win over everybody because we are Ukraine,” Zelenskyy said.
Experts and Ukrainian officials said the broad Russian offensive would likely cause massive humanitarian suffering.
“Resort to violence to settle territorial disputes causes incalculable damage to people and property,” David Miliband of the International Rescue Committee, an aid group, said in a statement. “We have seen a growing Age of Impunity in conflicts around the world, and deplore this latest evidence of major states treating the [United Nations] Charter as an optional extra in their decision-making.”
Liza Hearon and Nick Visser contributed to this article.