The United States and its allies have ramped up arms shipments to Kyiv ahead of Russia's announced offensive in eastern Ukraine, as Moscow tries to salvage its nearly two-month-old campaign.
Ukrainian forces have used Western weapons including Stinger and Javelin missiles along with drones, like the Turkish Bayraktar TB2 and U.S.-made Switchblade, effectively to target Russian positions.
The White House said earlier on Thursday that over 121 Phoenix Ghost Tactical Unmanned Aerial Systems would be provided to Ukraine as part of the new arms package.
The Pentagon said the Ghost drones are well suited for the coming fight in Ukraine's Donbas region, which officials have described as flat terrain reminiscent of the U.S. state of Kansas.
"In discussions with the Ukrainians again about their requirements, we believed that this particular system would very nicely suit their needs, particularly in eastern Ukraine," Pentagon spokesman John Kirby said, without elaborating.
Little else is known about the drones, including their range and precise capabilities, and Kirby declined to offer more details about them.
Still, he did say they were designed mainly for striking targets.
"This unmanned aero-system is designed for tactical operations, in other words, largely but not exclusively to attack targets," he added.
A small number of Ukrainians have been trained in the United States on how to operate Switchblade drones, single-use weapons that fly into their targets and detonate on impact.
Kirby said training for the Ghost drones would be similar to the training on the Switchblade. But he declined to detail training plans or say how many Ukrainians would be trained on the new system.
The Ghost drones have not yet been delivered to Ukraine.
Earlier on Thursday, Kirby said the drones had been rapidly developed for Ukraine. But later, at a news conference, he clarified that development had started before the Russian invasion on Feb. 24.
Kirby also mentioned U.S. Defense Secretary Lloyd Austin will host Ukraine-focused defence talks with allies at Ramstein Air Base in Germany on April 26, the Pentagon said on Thursday. Kirby did not say how many allies would participate.