President Zelenskyy has called on the West to speed up deliveries of weapons systems as troops move to consolidate control over the northeastern territory seized back from Russia.
Since Moscow abandoned its main hold in northeastern Ukraine on Saturday, marking its worst defeat since the early days of the war, Ukrainian troops have recaptured dozens of towns in a shift in battleground momentum.
A senior US military official said Russia has largely ceded territory near Kharkiv in the northeast and pulled many of its troops back over the border.
Washington and its allies have provided Ukraine with billions of dollars in weapons that Kyiv says have helped limit Russian gains. In a video address late on Monday, Zelenskyy said Ukraine and the West must “strengthen cooperation to defeat Russian terror.”
US Secretary of State Antony Blinken said Ukrainian forces have made “significant progress” with Western support.
Washington announced its latest weapons program for Ukraine last week, including ammunition for HIMARS anti-rocket systems, and has previously sent Ukraine NASAMS surface-to-air missile systems, which are capable of shooting down aircraft.