The United States has approved the sale of 500 Patriot missiles to Ukraine, a critically-needed munition for defence against escalating Russian aerial attacks.
However Ukrainian President Volodymyr Zelensky has warned it could take "several years" for the deliveries to arrive.
The US State Department said the advanced PAC-3 interceptor missiles would cost $2.1bn (£1.6bn) and would be "funded entirely" by Kyiv's allies in Europe and Canada.
On Friday night Zelensky repeated his calls for the US to speed up the release of its Patriots - the only effective weapon in downing Russia's deadly ballistic missiles.
The latest move comes after a row between Zelensky and Donald Trump earlier this month when the US eased sanctions on Russia as part of a deal to secure Russian diesel.
The US president stated it was time for Ukraine to get a new leader to strike a deal to end the war with Russia. Moscow launched a full-scale invasion of Ukraine in February 2022, having earlier seized Crimea and parts of Donbas in the east.
Tensions eased after Zelensky held talks with US envoys in Oslo on 20 October.
In Friday's statement, the State Department said "this proposed sale will support the foreign policy and national security objectives of the United States by improving the security of a partner country that is a force for political and economic stability in Europe".
It said "Ukraine will pay for this purchase with donations from Canada, Germany, and Norway via the JUMPSTART program and national funds, financed by the European Union's Ukraine Support Loan".
The statement said the "principal contractor" would be American company Lockheed Martin, adding that "no US funds are involved in this sale".
Meanwhile, at the G20 foreign ministers' meeting European diplomats protested over the presence of Russia's Foreign Minister Sergei Lavrov by refusing to stand for an official photograph.
The meeting is being hosted in Atlanta by US Secretary of State Marco Rubio.
"Let me say this directly to the Russian Foreign Minister: We all know who the aggressor in this war is," UK Foreign Secretary Ed Miliband told Lavrov at the summit, accusing his government of killing innocent civilians in Ukraine.
Zelensky said earlier this week that Ukraine had been waiting almost a month for the US to sign off on critical missile supplies which his country was running critically low on.
In a post on X late on Friday, he welcomed the US announcement but said Ukraine needed the Patriot missiles "right now".
He said Russia was intensifying its attacks on key energy infrastructure ahead of winter with "more than 30 Russian strikes" on "critical parts" of Ukraine's power grid over the past two weeks.
Kyiv desperately needs the interceptors but there is a global shortage of the munitions due to their use by the US in its war against Iran.
It is not clear what the production schedule will be for the Patriots - but it is understood the order is for new builds rather than existing missiles, meaning there is unlikely to be any kind of rapid delivery to Ukraine.
Patriots also have lengthy production times, with only 600 missiles produced per year according to the US Department of Defence.
In July, Trump said Washington had "not agreed" to license Ukraine to produce Patriots - three weeks after offering the country such a right.
Source: BBC
--Agencies
