The Pentagon formally approved in late June a plan to help treat wounded Ukrainian troops at a US military hospital in Germany, a defense official said on Tuesday.
Nearly five months since President Vladimir Putin ordered an invasion of Russia's neighbor, its forces are grinding through the Donbas region of eastern Ukraine and occupy around a fifth of the country.
The Kyiv government said in June that 100 to 200 Ukrainian troops were being killed per day.
A US official, speaking on the condition of anonymity, said no Ukrainian troops had been treated so far and US troops would not be going into Ukraine to bring Ukrainian personnel out.
It is unclear how many Ukrainian troops have been wounded but thousands of civilians have died and millions have fled. Russian artillery barrages and air strikes have pulverized cities.
It is unclear if any Ukrainian troops have been treated in other countries, such as neighboring Poland.
Ukrainian troops would be treated at Landstuhl Regional Medical Center if needed, the official said.
Adjacent to the Ramstein Air Base southwest of Frankfurt, it is the largest US military hospital outside the continental United States.
The United States has already been training Ukrainian forces in Germany and provided more than $8 billion in security assistance to the Kyiv government.