Putin’s Bravado Puts to Test Western Determination to Help Ukraine

 U.S. Secretary of State Antony Blinken's visit to Ukraine this week reflects the Biden administration's concern about the danger of Russian aggression against its western neighbor. Though President Vladimir Putin has temporarily eased tensions by ordering Russian troops to pull back from the border, he remains determined to undermine the Ukrainian government's control over its own territory. The U.S. and its NATO allies should meet the threat with a coordinated response — which begins with providing Ukraine with the weapons necessary to defend itself.

 In recent weeks, the seven-year-old conflict between Ukrainian troops and Russia-backed separatists in Ukraine's Donbas region has intensified, with Russia nearly doubling the size of its forces along the Ukrainian border and in Crimea, which it annexed in 2014. Russia's deployment of more than 100,000 troops to the region — along with tanks, warplanes, amphibious assault ships and reconnaissance drones — raised the specter of an offensive against Ukraine, a country of more than 40 million. Ukraine's president, Volodymyr Zelenskiy, said in an address to the nation that he was "ready" for war with Russia, while offering to meet with Putin "anywhere" in the conflict zone. After delivering a bellicose speech of his own, Putin announced that troops sent to the border region would retreat to their bases, though it's unclear when and how quickly they plan to do so.

Western leaders should make clear their commitment to Ukraine's security — and back up their words with action.

On this score, President Joe Biden's administration has been more consistent than France and Germany, which initially called on both sides to de-escalate the crisis, rather than place blame squarely on Putin. Given Putin's goal...