Siren sounds in Kyiv, shelling hits Ukrainian military units as Russia launches 'full-scale invasion'

KYIV: An emergency siren sounded around Kyiv on Thursday (Feb 24) morning and the defence minister said that Ukrainian units, military control centres and airfields in Ukraine's east were under intensive Russian shelling.

The military said that Ukraine's air force was trying to repel a Russian air attack, adding that reports of Russian troops landing in Odessa were false.

The country's border guards said Ukraine was coming under Russian artillery fire and land invasion along its northern and southern borders, and that Ukrainian forces were returning fire.

They added that Russian forces were supported by Belarus and an attack had been launched from Crimea, the Russian-occupied peninsula region on Ukraine's southern flank.

"Attacks on border units, border detachments and checkpoints are carried out with the use of artillery, heavy equipment and small arms," the border guards' statement said.

"The work of enemy sabotage and reconnaissance groups is also recorded."

The statement was issued as a Ukrainian interior ministry official reported the fall of the previously government-held town of Shchastya, on the eastern frontline with a rebel-held enclave.

Earlier on Thursday, Ukrainian leader Volodymyr Zelensky said Russia was attacking his country's "military infrastructure" and border guards, but urged citizens not to panic and vowed victory.

In a video message posted on Facebook after Russian President Vladimir Putin announced the launch of a military operation against Ukraine, Zelensky also introduced martial law across the country, adding that he had spoken by phone with US President Joe Biden.

"There are strikes on military and other important defence facilities, border units are under attack, the situation in the Donbas has degraded," a statement on Zelensky's website read.

"The Armed Forces of Ukraine, all special and law enforcement agencies of the state are on alert. The National Security and Defense Council is working in an emergency mode.

"Martial law will be imposed."

Ukraine's Foreign Minister Dmytro Kuleba also accused Putin of launching a "full-scale invasion".

"Putin has just launched a full-scale invasion of Ukraine. Peaceful Ukrainian cities are under strikes," Kuleba tweeted.

"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."

Meanwhile, Ukraine's ambassador to the United Nations implored the Security Council, chaired by Russia, to "do everything possible to stop the war" against his country.

"It is the responsibility of these bodies to stop the war," Sergiy Kyslytsya told a late-night meeting of the 15-member council which began shortly after Russian President Vladimir Putin announced a military operation in Ukraine.

Kyslytsya urged Russia's UN ambassador Vassily Nebenzia, which currently holds the rotating presidency of the council, to "call Putin, call (Foreign Minister Sergey) Lavrov to stop (the) aggression".