Diplomatic activity quickened on multiple fronts Monday as Russia’s war on Ukraine entered an uncertain new phase, with Russian President Vladimir Putin’s forces widening their bombardment of Kyiv and other cities, hundreds of civilians escaping the devastated port of Mariupol, and the United States warning China over its deepening alignment with an isolated Russia.

There were no breakthroughs, either at the negotiating tables or on the battlefield. But as the human cost of the war continued to mount, the flurry of developments suggested that people were groping for a way out of the crisis — or, failing that, for ways to prevent it from mutating into a wider proxy war.

In Rome, U.S. President Joe Biden’s top national security aide, Jake Sullivan, met with a top Chinese foreign affairs official, Yang Jiechi, to try to peel away one of Putin’s few potential allies, after reports — denied by Moscow and Beijing — that Russia had sought military aid from China, and that Chinese leaders were open to such a request. Sullivan, a Biden administration official said, had expressed "deep concerns” about "China’s alignment at this time.”