WASHINGTON — Yemen’s Houthi rebels appear to be exploring a new technical step in the domestic manufacture of their attack drones by using hydrogen fuel cells, which would give their unmanned aerial vehicles (UAVs) longer range and quieter engines, according to a new analysis.

Chinese-made hydrogen gas canisters were among smuggled drone components recovered by Yemeni National Resistance Forces (NRF) and shown to researchers at Conflict Armament Research (CAR) — a UK-based nongovernmental organization tracking new trends in the international illicit arms trade — late last year.

The 20-liter canisters appeared to be deliberately mislabeled as “oxygen cylinders,” researchers with CAR determined, owing to included instructions that described them as containing hydrogen. The instructions also explicitly state the canisters’ use in UAVs, according to the new report released Thursday by CAR. 

The NRF, led by Yemeni general Tareq al-Saleh, told CAR investigators the components were seized aboard a cargo vessel in the Red Sea in August 2024 that was bound for the port at Salif, carrying chemical fertilizer, in Houthi-controlled territory.