Ukrainian President Volodymyr Zelensky said on Thursday that Russia was attacking his country's military infrastructure and border guards, but urged citizens not to panic and vowed to win.
Citing Channel News Asia, in a video message posted on Facebook after Russian President Vladimir Putin announced the launch of a military operation against Ukraine, Zelensky imposed martial law across the country.
And, Zelensky revealed, he had spoken by telephone with US President Joe Biden.
Earlier, Ukrainian Foreign Minister Dmytro Kuleba said Russia was launching a "full-scale invasion" as explosions were heard in cities across the country.
"Putin has just launched a full-scale invasion of Ukraine. Peaceful Ukrainian cities are under attack," Kuleba tweeted, as quoted by Al Jazeera.
"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," he stressed.
The Interfax news agency reported citing local media that explosions could be heard in the distance from the Ukrainian capital, Kyiv. Meanwhile gunfire was heard near Boryspil Airport.
According to Interfax as reported by Reuters, rocket attacks occurred against military facilities throughout Ukraine. And Russian troops have landed in the Southern Ukrainian port cities of Odessa and Mariupol.