The U.S. move won’t have an immediate impact on the battlefield, where Kyiv’s forces are struggling to stem a relentless Russian offensive in eastern Ukraine. Ukrainian forces have slowed Russian advances along the roughly 1,000-kilometer (600-mile) front line, where Russia is slowly gaining ground at a huge human and material cost.

Hours after the U.S. suspended military aid for Ukraine, the European Union proposed a $158 billion fund to bolster military spending and support Kyiv.

Washington's suspension of military assistance will not lead to a sudden collapse of Ukraine's defensive lines, but it could have a real impact on the war within months, undermining air defences and precision strike capabilities in particular.