Russian President Vladimir Putin announced on Feb. 21, 2022, that he had recognized two Russian-backed separatist areas in eastern Ukraine, Donetsk and Luhansk, as independent states.

Ukrainian President Volodymyr Zelenskyy followed the announcement by saying that Ukraine had cut diplomatic ties with Russia. Putin then gave a speech on Feb. 24, 2022, announcing he would launch a "special military operation" in Ukraine.

Minutes after the announcement, explosions could be heard in Kyiv. What followed was a full-scale invasion of Ukraine, with thousands of troops crossing the country's borders. Here are the key events that occurred in the year since then.

-ABC News' Nadine El-Bawab

Ukrainian forces have killed 225 Russian fighters and injured another 306 in the past 24 hours in the Bakhmut area, according to Serhiy Cherevaty, the spokesman for the Eastern Group of Forces of the Ukraine army.

Russia and Ukraine have been locked in a brutal battle for the city in eastern Ukraine for months, with both sides seeing high rates of casualties.

Cherevaty said that in the last day, the occupiers in the area of Bakhmut and nearby villages -- including Orikhovo-Vasylivka, Bohdanivka and Ivanivskoho -- tried to attack Ukrainian positions 42 times. There were 24 combat clashes in the Bakhmut area alone.

In total, in the Bakhmut direction, the occupiers shelled Ukrainian positions 256 times with various types of artillery and multiple launch rocket systems, Cherevaty said. Of them, 53 shellings were in the area of Bakhmut itself.

-ABC News' Will Gretsky