US President Joe Biden announced more than $8 billion in military assistance for Ukraine on Thursday to help Kyiv "win this war" against Russian invaders, using a visit by President Volodymyr Zelenskiy to make a major commitment.

The aid includes the first shipment of a precision-guided glide bomb called the Joint Standoff Weapon, with a range of up to 81 miles. The medium-range missile gives Ukraine a major upgrade to the weapons it is using to strike Russian forces, allowing the Ukrainians to do it at safer distances.

The bomb, capable of striking targets with high accuracy, is to be dropped from fighter jets. Biden will not announce that Washington would let Ukraine use US missiles to hit targets deeper in Russia, a US official said.

Supporting Ukraine, which Russia invaded in February 2022, has been a US top priority, Biden said in a statement.

"That is why, today, I am announcing a surge in security assistance for Ukraine and a series of additional actions to help Ukraine win this war," said Biden, who leaves office in January.

The bulk of the new aid, $5.5 billion, is to be allocated before Monday's end of the US fiscal year, when the funding authority is set to expire. Another $2.4 billion is under the Ukraine Security Assistance Initiative, which allows the administration to buy weapons for Ukraine from companies rather than pull them from US stocks.

This will provide Ukraine with additional air defense, unmanned aerial systems and air-to-ground munitions, as well as strengthen Ukraine's defense industrial base and support its maintenance and sustainment requirements, Biden said.

Under his plan, the president said, the Defense Department will refurbish and provide Ukraine with an additional Patriot air defense battery and more Patriot missiles.

Biden ordered the Pentagon to expand training for Ukrainian F-16 pilots, including by supporting the training of an additional 18 pilots next year.

Zelenskiy thanked Biden and the U.S. Congress for the new military aid package, saying Ukraine would use it "in the most efficient and transparent manner."

"I am grateful to the United States for providing the items that are most critical to protecting our people," Zelenskiy said on X, mentioning the Patriot battery, drones and long-range missiles. (Reuters)