Russia is currently occupying about 20% of Ukraine's territory, Ukrainian President Volodymyr Zelenskiy told Luxembourg's parliament in a video address on Thursday.
"We have to defend ourselves against almost the entire Russian army. All combat-ready Russian military formations are involved in this aggression," he said, adding that the front lines of battle stretched across more than 1,000 kilometers.
Russian forces, backed by heavy artillery, control most of Sievierodonetsk - now largely in ruins - after days of fierce fighting in which they have taken losses, Britain's defense ministry said in its daily intelligence report.
Russia has accused the United States of adding "fuel to the fire" after President Joe Biden announced a $700 million weapons package for Ukraine that will include advanced rocket systems with a range of up to 80 km.
Zelenskiy told a forum in Slovakia on Thursday that Kyiv was grateful for the military aid so far but added: "Weapons supplies should be stepped up ... (to) ensure an inflection point in this confrontation."
