(CN) — Russian and Ukrainian forces were engaged in bitter combat in the capital Kyiv and other parts of Ukraine on Friday with casualties mounting in a war that has put Europe and the rest of the world on edge.

Russian troops were on the edge of Kyiv by the afternoon but were reportedly being held back by stiff opposition, though the state of the conflict remained highly uncertain due to spotty reporting from the field.

It has become increasingly clear that Russian President Vladimir Putin aims to remove Ukrainian President Volodymyr Zelenskyy from power and install a new regime in Kyiv, one that his foreign minister, Sergey Lavrov, said needs to represent all the people of Ukraine.

Reports from news outlets, social media and officials showed horrific images of explosions, burning buildings, downed aircraft, a barrage of artillery and other horrors. Friday was the second day of clashes after Putin launched the invasion in the early hours of Thursday.

The number of casualties continued to mount with the Ukrainian army saying more than 100 of its soldiers had been killed and that it had killed more than 1,000 Russian soldiers. These numbers are unconfirmed. The Ukrainian army said it was putting up a strong resistance to the Russian invasion and Kyiv pleaded for more help from the West.

Russia has portrayed this full-scale invasion of Ukraine as a “special military operation” for the “demilitarization” and “de-Nazification” of Ukraine.

Putin said he launched this increasingly bloody and catastrophic offensive against Ukraine to stop the country from becoming a nuclear-armed NATO member and to put an end to an eight-year-long simmering conflict in eastern Ukraine between pro-Russian separatists and Ukrainian forces.

Putin also is justifying his country's invasion as necessary to stop the mistreatment of millions of ethnic Russians in Ukraine and to eliminate neo-Nazi groups that his government says have grown in power since the U.S.-backed “Maidan Revolution” in 2013-2014 that led to the overthrow of a democratically elected pro-Russian president who sparked widespread anger by scrapping a deal to bring Ukraine closer to the European Union.

After the overthrow of pro-Russian President Viktor Yanukovych, Russia annexed Crimea and pro-Russian regions of eastern Ukraine known as the Donbas declared themselves independent, sparking an armed conflict that has left more than 14,000 people dead and up to 2 million out of their homes.

Following Yanukovych's removal from office, Ukraine signed the EU deal and has sought to speed up its entry into the NATO alliance, further angering the Kremlin.

International condemnation of Russia's invasion grew on Friday and saw Western allies impose more sanctions, including a decision by the EU to freeze the personal assets of Putin and Lavrov. It is very rare for the head of a state to be sanctioned.

Additionally, Europe's soccer federation moved the continent's most important tournament, the Champions League championship, away from St. Petersburg to Paris and the Formula One car racing organization canceled a race scheduled to take place in Sochi, Russia. Protests against the war broke out in European cities and in Moscow, though protesters there were arrested.