The U.S. is halting deliveries of key air defense missiles to allies, directing shipments to Ukraine instead in a bid to help bolster the country amid a continuing aerial barrage from Russia, the White House said.

Raytheon’s Patriot and NASAMS surface-to-air missiles will both be redirected to Ukraine as part of a "difficult but necessary decision” to reprioritize planned deliveries, White House National Security Council spokesman John Kirby told reporters Thursday.

The move comes as some European countries, including Spain and Greece, have so far balked at requests to transfer their systems to Ukraine. But Kyiv has described air defense systems — and particularly advanced Patriots — as crucial for protecting population centers and critical infrastructure, including the country’s badly battered electrical grid.