About 100 Ukrainian troops are expected head to Oklahoma's Fort Sill as soon as next week to begin training on the Patriot missile defence system.
For months, Ukraine has been asking the US to provide the surface-to-air guided missile defence system because it can target aircraft, cruise missiles and shorter-range ballistic missiles.
During his late-December visit to the US, Ukrainian President Volodymyr Zelenskyy said the battery would make a significant difference in bolstering Kyiv's defences against Russia's invasion.
The number of Ukrainians heading to Fort Sill was approximately the number it takes to operate one battery, Pentagon spokesman Air Force General Pat Ryder said.
He said they would focus on learning to operate and maintain the system.
Kyiv's decision to take troops off the battlefield to train across the Atlantic in the US is unusual, although Ukraine has sent forces for short-term training at European bases for other complex systems it has received, such as on the longer-range High Mobility Artillery Rocket System (HiMARS).
Patriot training normally takes several months, but "the longer those troops are off the line, they're not actually engaged in combat", General Ryder said, so the training would be shortened.
Fort Sill was selected because it already runs Patriot training schools, he said.
The US pledged one Patriot battery in December as part of one of several large military assistance packages it has provided Ukraine in recent weeks.
Last week, Germany pledged an additional Patriot battery.
Each Patriot battery consists of a truck-mounted launching system with eight launchers that can hold up to four missile interceptors each, a ground radar, a control station and a generator.
The US Army said it has 16 Patriot battalions.
Patriot batteries will complement a variety of air defence systems that both the US and NATO partners have pledged to Ukraine, as it faces an evolving barrage of missiles and drones against its civilian population and infrastructure from Russia in the nearly 11-month-old conflict.
In the last few months Germany has pledged four IRIS-T air defence systems.
The US has also pledged eight mid-range National Advanced Surface-to-Air Missile Systems (NASAMS) as well as Avenger air defence systems.
AP