As Russia pushes forward, Ukrainian soldiers say U.S. aid delays have left them exposed

KYIV, Ukraine — On Ukraine’s front lines, soldiers have their eyes on the enemy slowly advancing across the country’s muddy fields — and on Washington, where an ally’s inaction is doing as much to dent their morale.

“The situation on the battlefield is getting worse every week,” one soldier serving in the southern Zaporizhzhia region told NBC News.

Russia’s military has Ukraine on the defensive, taking advantage of an army that is vulnerable after nearly two years of war: short of soldiers, dealing with leadership upheaval and critically low on ammunition. New military aid remains stalled in Congress, and a shortage of supplies has contributed to the surrender of a key eastern city and eroded morale among units that find themselves outmanned and outgunned.

NBC News spoke to five soldiers across the war's more than 600 miles of front lines, as well as military analysts, who offered a bleak assessment of Ukraine’s prospects with support from its Western backers in doubt.