The US will send about 225 million dollars (£175 million) in military aid to Ukraine, officials said on Thursday.
The new package will includes ammunition Kyiv’s forces could use to strike threats inside Russia to defend the city of Kharkiv from a heavy Russian assault.
The officials said the aid includes munitions for the High Mobility Artillery Rocket System, or HIMARS, as well as mortar systems and an array of artillery rounds.
Under a new US directive, Ukraine can use such weapons to strike across the border into Russia if forces there are attacking or preparing to attack.
That change, however, does not alter US policy that directs Ukraine not to use American-provided ATACMS or long-range missiles and other munitions to strike offensively inside Russia, according to US officials.
The new aid package comes as President Joe Biden used his speech at the American cemetery in Normandy on the 80th anniversary of D-Day to vow that the US “will not walk away” from the defence of Ukraine and allow Russia to threaten more of Europe.
To do so, he said, would mean the US has forgotten “what happened here on these hallowed beaches”.
Mr Biden is expected to meet with Ukrainian President Volodymyr Zelensky in Paris on Friday.
On Wednesday, a Western official and a US senator said Ukraine has used US weapons to strike inside Russia.
A June 3 report from the Institute for the Study of War suggests that Ukrainian forces used a HIMARS system to strike a Russian S-300/400 air defence battery in the Belgorod region in recent days.
The new aid package is being provided through presidential drawdown authority, which pulls systems and munitions from existing US stockpiles so they can go quickly to the war front.
Officials said the aid package also includes missiles for the Hawk air defence system, Stinger anti-aircraft missiles, Javelin and AT-4 anti-armour systems, 155mm Howitzers, armoured vehicles, trailers, patrol boats, demolition materials and a wide range of other spare parts and equipment.
Ukrainian officials have pressed the US to allow Kyiv’s forces to defend themselves against attacks originating from Russian territory.
Kharkiv, Ukraine’s second-largest city, sits just 20km (12 miles) from the Russian border and has come under intensified Russian attack.
In response to Nato allies allowing Ukraine to use their arms to attack Russian territory, Russian President Vladimir Putin warned on Wednesday that Russia could provide long-range weapons to others to strike Western targets.
The additional HIMARS munitions are part of a US effort to beef up Ukraine’s use of the key weapons.
The State Department last month approved a proposed emergency sale of HIMARS systems to Ukraine for an estimated 30 million dollars. It said Ukraine has asked to buy three of the rocket systems, which would be funded by the government of Germany.
