Russian President Vladimir Putin's invasion of Ukraine three years ago has turned into Europe’s largest conflict since World War II.

Slowly but steadily this summer, Russian troops are forging through Ukraine’s outgunned and undermanned defenses along the front line of the battlefield in a relentless onslaught, prompting the West to push for new weapons and strategies to shore up Kyiv.

Despite three weeks of Russian bombardment, Ukraine has kept up a stiff defense of its cities by using Turkish-made drones to carry out attacks on the invaders with a lethal effectiveness that has surprised Western military experts.