Russian troops bore down on Ukraine’s capital today, with explosions and gunfire sounding in the city as the invasion of a democratic country fueled fears of wider war in Europe and triggered new international efforts — including direct sanctions on President Vladimir Putin — to make Moscow stop.

Amid reports of hundreds of casualties from the warfare — including shelling that sliced through a Kyiv apartment building and pummeled bridges and schools — there also were growing signs that Russia may be seeking to overthrow Ukraine’s government, which U.S. officials have described as Putin’s ultimate objective.

Ukraine President Volodomyr Zelenskyy appealed for a cease-fire and warned in a bleak statement that multiple cities were under attack. “Tonight they will storm,” he said.

U.S. defense officials believe the Russian offensive has encountered considerable resistance and is proceeding slower than Moscow had envisioned. That’s something of a reversal from the run-up to the attack, when U.S. officials appeared more alarmed than their counterparts in Kyiv at the pace of Russian operations.

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