The Biden administration has refused to hand over advanced drones to Ukraine, according to a report from the Wall Street Journal.
Ukraine had requested the weapons to help fight Russia, but the Pentagon refused.
US officials were reportedly concerned that providing the drones could escalate the conflict and signal that America was supplying weapons capable of targeting positions inside Russia.
Western officials have refused to get directly involved in the conflict to avoid an all-out war with Russia.
Last week, the US announced an additional $400 million in military aid to Ukraine.
This included retrofitting T-72 tanks and missiles for HAWK air defense systems.