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President Joe Biden on Wednesday announced an additional $800 million in US security aid for Ukraine that will include helicopters, armoured personnel carriers and artillery systems, marking a deepening American military commitment toward the war-torn country.
The latest tranche of materiel means the US has sent nearly $2 billion in military assistance to Ukraine since Russia invaded on February 24.
"The Ukrainian military has used the weapons we are providing to devastating effect," Mr Biden said in a statement.
"As Russia prepares to intensify its attack in the Donbas region, the United States will continue to provide Ukraine with the capabilities to defend itself."
The latest package will for the first time include 18 155 mm Howitzer artillery systems, Pentagon spokesman John Kirby said.
The US will also send 10 counter-artillery radar systems, 200 M113 armoured personnel carriers, 100 Humvees and 300 more Switchblade drones, according to a list released by the Pentagon. Ukrainians will need some training on radars and artillery systems, Mr Kirby said.
The Pentagon will also send unmanned surface vessels for coastal defence as well as individual chemical-biological protective suits and detection systems.
Mr Biden made the announcement after speaking with Ukrainian President Volodymyr Zelenskyy, who has for weeks been pushing western nations to quickly increase weapons supplies.
The White House said last week that it has provided more than $1.7 billion in security assistance to Ukraine since the February 24 invasion of Ukraine that Russia calls a “special military operation.”
Previous weapons shipments have included defensive anti-aircraft Stinger and anti-tank Javelin missiles, as well as ammunition and body armour.
Mr Biden said the steady supply of western weapons to Ukraine has been "critical" in sustaining its fight against the Russian invasion.
It has helped ensure that Russian President Vladimir Putin "failed in his initial war aims to conquer and control Ukraine," Mr Biden added.
At the Pentagon, a senior US defence official said another delivery of Javelin missiles was set to arrive in Ukraine in the next 24 hours.
The US also helped "two airlift deliveries from two different nations," the official said elaborating.
Russia has now fired more than 1,550 missiles into Ukraine and assessed that the city of Mariupol remains contested, the official said.
"We still hold that Ukrainian forces are in Mariupol and they're defending it," the official said.
Following seven weeks of fighting, the US official continued to point to low morale on the Russian side.
"We do have indications... of frustration, not only at the enlisted level, with what they're being asked to do, but with their officers, their leadership, frustrated with their troops performance, frustrated with their colleagues performance," the official said.
The new shipment of aid will add to more than $2.4 billion in security assistance the US has provided to Ukraine since MrBiden took office last year, including more than $1.7 billion since Russia invaded Ukraine on February 24.
Agencies contributed to this report