Ukrainian President Volodymyr Zelensky briefly addressed his nation about 90 minutes after the Russian attack began early Thursday morning local time. Zelensky declared martial law and vowed to resist the Russian invasion while urging his citizens to remain calm.

“We are introducing martial law across the country. No panic. We are ready for anything. We are going to win because we are Ukrainians,” Zelensky said, apparently speaking into a tablet, phone, or laptop computer.

“Dear Ukrainian citizens, this morning President Putin announced a special military operation in Donbas. Russia conducted strikes on our military infrastructure and our border guards. There were blasts heard in many cities of Ukraine,” he said.

Russian President Vladimir Putin speaks with Russia’s local authorities during a video link meeting at the Novo-Ogaryovo state residence outside Moscow on October 4, 2021. (Photo by EVGENY PAULIN/SPUTNIK/AFP via Getty Images)

Zelensky said he had just spoken by telephone with U.S. President Joe Biden, and the United States has “already started uniting international support” for Ukraine.

“Stay at home if you can. We are working. The army is working. The whole sector of defense and security is working,” he advised his citizens.