Russian forces have fired missiles at Ukrainian cities and landed troops on its south coast, officials and media say, after President Vladimir Putin authorised what he called a special military operation in the east.

Shortly after Putin spoke in a televised address on Russian state TV, explosions could be heard in the pre-dawn quiet of the Ukrainian capital of Kyiv.

Gunfire rattled near the capital’s main airport, the Interfax news agency said.

“Putin has just launched a full-scale invasion of Ukraine. Peaceful Ukrainian cities are under strikes,” Ukrainian Foreign Minister Dmytro Kuleba said on Twitter.

“This is a war of aggression. Ukraine will defend itself and will win. The world can and must stop Putin. The time to act is now.”

US President Joe Biden said his prayers were with the people of Ukraine “as they suffer an unprovoked and unjustified attack by Russian military forces”.

Russia has been demanding an end to NATO’s eastward expansion.

Putin said he had authorised the special military operation in breakaway areas of eastern Ukraine after Russia had been left with no choice but to defend itself against what he said were threats emanating from modern Ukraine.

“Russia cannot feel safe, develop, and exist with a constant threat emanating from the territory of modern Ukraine,” Putin said. “All responsibility for bloodshed will be on the conscience of the ruling regime in Ukraine.”

The full scope of the Russian military operation was not immediately clear but Putin said: “Our plans do not include the occupation of Ukrainian territories. We are not going to impose anything by force.”

Speaking as the UN Security Council held an emergency meeting in New York, Putin said he had ordered Russian forces to protect the people and appealed to the Ukrainian military to lay down their arms.

Ukraine’s military command centres in Kyiv and the city of Kharkiv in the northeast had been struck by missiles, a Ukrainian news site cited an official as saying, while Russian troops had landed in the southern port cities of Odessa and Mariupol, Interfax Ukraine reported.

Explosions also rocked the breakaway eastern Ukrainian city of Donetsk and civilian aircraft were warned away from the region.

Hours earlier, pro-Russian separatists issued a plea to Moscow for help to stop alleged Ukrainian aggression – claims the United States dismissed as Russian propaganda.

Ukrainian President Volodymyr Zelenskiy declared a state of war for the country and urged citizens not to panic.

Biden said Putin had chosen a premeditated war that would bring a catastrophic loss of life and human suffering.

“Russia alone is responsible for the death and destruction this attack will bring, and the United States and its Allies and partners will respond in a united and decisive way. The world will hold Russia accountable,” he said.

He said he would announce further sanctions on Russia on Thursday, in addition to financial measures imposed this week.

NATO Secretary-General Jens Stoltenberg strongly condemned Russia’s “reckless and unprovoked attack” on Ukraine and said NATO allies would meet to tackle the consequences of Moscow’s “aggressive actions”.

UN Secretary-General Antonio Guterres made a last-minute plea to Putin to stop the war “in the name of humanity’, after the Russian leader announced the military operation.

“President Putin, in the name of humanity, bring your troops back to Russia,” Guterres said, speaking after the Security Council meeting.

Ukraine earlier restricted civilian flights in its airspace due to “potential hazard”, hours after a conflict zone monitor warned airlines should stop overflights over the risk of an unintended shooting down or cyber attack.

Shelling had intensified since Monday when Putin recognised two separatist regions as independent and ordered the deployment of what he called peacekeepers, a move the West called the start of an invasion.

The Ukrainian government on Wednesday also announced compulsory military service for all men of fighting age.

Western countries and Japan imposed sanctions on Russian banks and individuals but have held off their toughest measures until an invasion began.

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