The new arms deliveries represent a stark shift from Western support for Ukraine in the earliest days of the war, when U.S. and European officials, unsure of how long Ukraine could hold out against a massive Russian invasion, were wary of delivering heavy weapons that could in turn fall into Russian hands. The deliveries also reflect a shift away from defensive systems like anti-tank rockets to more offensive weapons that Ukraine needs at a critical stage of the war.

The Czech Republic opened the floodgates earlier this month by shipping tanks to Ukraine, becoming the first NATO country to do so since Russia launched its invasion on Feb. 24. The Czech Republic has also sent Ukraine infantry fighting vehicles and artillery systems.

Other NATO countries have followed suit with their own shipments of high-end military hardware across NATO borders into Ukraine. Slovakia sent Ukraine an advanced S-300 air defense system, and the United States on Wednesday announced it would supply Ukraine with an additional $800 million worth of military hardware. That shipment includes 11 MI-17 helicopters, 200 M113 armored personnel carriers, 100 Humvees, 300 Switchblade “kamikaze” drones, heavy howitzers, thousands of shells, and other munitions.