Russian military forces could use chemical weapons to create a “pretext” for a major new invasion of Ukraine, according to Secretary of State Antony Blinken.

Blinken, in an unexpected appearance before the United Nations Security Council, said Vladimir Putin is already taking “steps down a path to war,” although he allowed that the Russian president could change course. Yet a barrage of shelling in eastern Ukraine, paired with Russian allegations against Kyiv, spurred Blinken to race to New York City to intervene in a meeting that Russian officials had scheduled to accuse the Ukrainian central government of blocking a peace agreement to end the crisis.