Ukraine's president has praised the US for including tank-busting armoured vehicles in its package of military aid, saying they are "exactly what is needed" for Ukrainian troops battling Russian forces.
The White House on Friday announced $3.75bn (£3.1bn) in weapons and other aid for Ukraine and its neighbours on Nato's eastern flank, which came as Moscow said its troops were observing a short ceasefire for Orthodox Christmas.
Ukrainian officials denounced the unilateral 36-hour truce as a ploy and said it appeared to have been ignored by some of Moscow's forces pressing ahead with the nearly 11-month invasion.
Russia's Defence Ministry had insisted that its forces along the 680-mile frontline were observing the ceasefire but returned fire when attacked.
The military assistance announced by the White House was the biggest to date for Kyiv, and for the first time, it included Bradley armoured vehicles armed with anti-tank missiles.
In his nightly televised address on Friday, Ukraine President Volodymyr Zelensky called it "a very powerful package".
"For the first time, we will get Bradley armoured vehicles — this is exactly what is needed. New guns and rounds, including high-precision ones, new rockets, and new drones. It is timely and strong," he said.
He thanked President Joe Biden, US legislators and "all the Americans who appreciate freedom, and who know that freedom is worth protecting".
Officials said it was unclear whether Moscow was abiding by a unilateral 36-hour ceasefire for Orthodox Christmas which Ukraine denounced as a ploy.
In the fiercely contested Luhansk region of eastern Ukraine, regional governor Serhiy Haidai reported continued Russian shelling and assaults.
He said that in the first three hours of the ceasefire supposed to start on Friday, Russian forces shelled Ukrainian positions 14 times and stormed one settlement three times. The claim could not be independently verified.
Russia's Defence Ministry alleged on Friday that Ukrainian forces continued to shell its positions, and said its forces returned fire.
Ukrainian authorities on Saturday reported attacks elsewhere in the previous 24 hours although it was not clear whether the fighting was before or after the ceasefire started.
The Ministry of Defence (MOD) in its latest defence intelligence update on the situation in Ukraine said that "fighting has continued at a routine level into the Orthodox Christmas period".
Ukrainian officials dismissed Moscow's unilateral order for a 36-hour pause as a ploy to buy its struggling invasion forces time to regroup.
It was due to end on Saturday night — at midnight Moscow time, which is 11 pm in the Ukrainian capital, Kyiv.
Ukrainian and western officials portrayed the announcement as an attempt by President Vladimir Putin to take the moral high ground, while possibly seeking to snatch the battlefield initiative and rob the Ukrainians of momentum amid their counter-offensive of recent months.