Several attacks have been repulsed in the eastern Donetsk region in the last 24 hours, according to Ukraine’s military.
Russian forces claim to be on the verge of capturing the eastern city of Bakhmut, which has been the site of intense fighting for months.
The head of Russia’s Wagner private army claims the country is “practically encircled” with few options for escape.
The United States has announced an additional $400 million (£333 million) in military aid to replenish Kyiv’s depleted ammunition stocks.
Col Gen Oleksandr Syrskyi, commander of Ukraine’s ground forces, visited Bakhmut on Friday for talks with local commanders about how to strengthen front-line forces.
For over six months, Russian troops have been attempting to take the city.
Ukraine’s President Volodymyr Zelensky warned this week that the situation on the eastern front line was becoming “more and more difficult”.
Ukraine’s ever-dwindling ammunition stocks are a major source of concern, as the high-intensity war with Russia shows no signs of abating.
US Secretary of State Antony Blinken said the country’s latest package included high-precision Himars artillery rockets and howitzers “which Ukraine is using so effectively”.
President Zelensky earlier stressed that artillery and shells were needed to “stop Russia”.
In addition, the US is sending tactical bridges ahead of Ukraine’s expected offensive.
The delivery of such equipment, which allows armoured vehicles to cross rivers and ditches, comes as several Ukrainian military officials and experts have suggested that the operation could begin in the coming weeks.
Separately, a partial evacuation was ordered on Thursday in Kupiansk, Kharkiv region, which was liberated from Russian occupation last September.
Due to “constant” shelling by Russian forces, regional authorities advised families with children and people “with limited mobility” to leave.
According to Zelensky, the situation in the front-line city is deteriorating.
“This military assistance package includes more ammunition for US-provided Himars and howitzers, which Ukraine is using so effectively to defend itself,” Mr Blinken said in a statement on Friday.
Washington would also send “ammunition for Bradley Infantry Fighting Vehicles, Armoured Vehicle Launched Bridges, demolition munitions and equipment, and other maintenance, training, and support,” he added.
Himars were extremely effective during Ukraine’s lightning counter-offensive late last year, which brought almost the entire Kharkiv region back under Kyiv’s control.
These advances, along with the liberation of Kherson in the south, were the most significant front-line changes since Russia’s withdrawal from areas around Kyiv in April.
America’s top diplomat emphasised in his statement that “the United States also continues to rally the world to support Ukraine” in defending its sovereignty and territorial integrity.
The new US military aid package was announced as US media reported that Ukraine may be running dangerously low on artillery stocks after more than a year since Russia launched its full-scale invasion.
Both Ukraine and Russia are thought to be firing tens of thousands of artillery shells per day in what has been described as a high-intensity attrition war in recent months.
The Ukrainian military has not publicly commented on the reported ammunition shortage.
However, President Zelensky on Thursday said that “artillery is number one that we need”.
He went on to say that Kyiv would also need “a large quantity of shells” and warplanes to “evict” Russian troops from Ukrainian territory.
Military assistance to Ukraine was expected to be the main topic of discussion when US President Joe Biden met German Chancellor Olaf Scholz in Washington on Friday.
Mr. Biden thanked the German Chancellor for his country’s “unwavering” support for Ukraine.
Mr Scholz said it was important to stress that this would continue “as long as it takes and as long as is necessary”.
A number of Ukraine’s Western allies have pledged to send tanks and artillery, but Kiev insists that this must happen much faster to deter further Russian aggression.