• When Russian President Vladimir Putin invaded Ukraine on Feb. 24 in an unprovoked act of aggression, many expected a quick victory.Six months later, the largest military conflict in Europe since World War II has turned into a grinding war of attrition. The Russian offensive has largely bogged down as Ukrainian forces increasingly target key facilities far behind the front lines, including in Russia-occupied Crimea.

When Putin declared the start of the “special military operation,” he urged Ukraine's military to turn against the government in Kyiv, reflecting the Kremlin's belief that the population would broadly welcome the invaders. Some of the Russian troops coming in from Moscow's ally of Belarus, just 200 kilometers (about 125 miles) north of the capital, reportedly brought their parade uniforms with them in preparation for a quick triumph.

Those hopes were quickly shattered by fierce Ukrainian resistance, backed by Western-supplied weapons systems to the government of President Volodymyr Zelenskyy.

Airborne troops sent to seize airfields around Kyiv suffered heavy losses and armored convoys stretching along the main highway leading to the capital were pummeled by Ukrainian artillery and scouts.

Despite numerous attacks on Ukrainian air bases and air defense assets, the Russian air force has failed to win full control of the skies and suffered heavy losses, limiting its ability to support ground forces.

One month into the war, Moscow pulled its troops back from areas near Kyiv, Kharkiv, Chernihiv and other major cities in a tacit acknowledgment of the blitz’s failure.

The Kremlin then shifted its focus to the Donbas, Ukraine's eastern industrial heartland, where Moscow-backed separatists had been fighting government troops since 2014 following Russia's annexation of the Crimean Peninsula.

Relying on their massive edge in artillery, Russian forces inched forward in ferocious battles that devastated the region. The strategic port of Mariupol on the Sea of Azov that became a symbol of Ukrainian resistance fell in May after a nearly three-month siege that reduced the city to ruins.

More than 2,400 Mariupol defenders who holed up at the giant Azovstal steel mill later surrendered and were taken prisoner. At least 53 of them died last month in an explosion at a prison in eastern Ukraine that Moscow and Kyiv blamed on each other.