(Reuters) -U.S. President Joe Biden said on Tuesday that his administration was "working that out now" when asked if the U.S. would lift restrictions on Ukraine's use of long range weapons in its war against Russia.

The U.S. has been reluctant to supply or sanction the use of weapons that could strike targets deep inside in Russia for fear it would escalate the conflict.

Kyiv's other allies have been supplying weapons, but with restrictions on how and when they can be used inside Russia, out of concern such strikes could prompt retaliation that draws NATO countries into the war or provokes a nuclear conflict.

Sources told Reuters last week that the U.S. was close to an agreement to give Ukraine such weapons, but that Kyiv would need to wait several months as the U.S. works through technical issues ahead of any shipment.