Defence secretary Lloyd J. Austin III on Wednesday urged western allies to redouble their military aid to Ukraine, warning that it “is facing a pivotal moment on the battlefield” in the nearly four-month war with Russia.

“We can’t afford to let up, and we can’t lose steam,” Austin told a meeting in Brussels of nearly 50 countries known as the Ukraine Defence Contact Group. He praised the flow of tanks, missiles and artillery provided to Ukraine so far, but said it was not enough, adding, “The stakes are too high.”

The US and its allies are expected to announce the delivery of more weapons and equipment later on Wednesday in response to increasingly urgent pleas from President Volodymyr Zelensky for more heavy arms to retake eastern territory lost to Russia and to defend against Russian missile attacks.

Ukraine is struggling to hold off a Russian onslaught in the east, with Moscow’s forces on the verge of capturing the strategic city of Sievierodonetsk. Kyiv has voiced frustration that many of the heavy weapons promised by its western allies have not arrived, as Russia uses its superior artillery to seize control of more of the eastern Donbas region.

The comments came as administration officials say they are increasingly looking at options for how to handle a sustained conflict — and whether a ceasefire, or a formal armistice similar to the one reached in Korea 70 years ago, would help or hurt the Ukrainian cause.

Their analysis, officials say, has been fairly pessimistic. They fear that President Vladimir V. Putin of Russia might use a cessation of hostilities to rebuild his military, and perhaps seek another opportunity to take all of Ukraine, his objective when the war began on February 24.

New York Times News Service