Washington/UNI: The United States struggles to supply the Ukrainian troops with effective counter drone systems to address the modern aerial threat, the Wall Street Journal said in a report, citing Western officials and analysts.

The US Defense Department promised the delivery of Vampire counter drone systems to Ukraine in August, but only approved a $40 million contract for the weapon last month, the report said on Monday.

The United States will not deliver the first four Vampire systems until mid-2023, with ten more units expected to arrive by year’s end, the report said.

Ukraine needs hundreds of counter drone systems around large cities, military facilities and infrastructure to meet the threat, Sam Bendett, a drone expert with the federally-funded Center for Naval Analyses said.

Vampire systems, short for Vehicle-Agnostic Modular Palletized ISR Rocket Equipment, tracks targets and intercepts them with laser-guided munitions.

The counter drone system is intended to fit in the back of a standard pickup truck, the report added.

The systems are meant to address the reported widespread use of drones by Russian forces. Washington and Kiev accuse Moscow of utilizing Iranian Shahed-136 drones in Ukraine. Moscow and Tehran have denied the accusations.