The US State Department approved the potential sale of 500 Patriot air defense interceptor missiles to Ukraine on Friday, according to a department release.

Kyiv uses the defensive weapons to blunt Russia’s continuous ballistic missile strikes on its territory, but Ukraine’s supply ran dry earlier this month, CNN previously reported. The deal is for the PAC-3 MSE variant of the Patriot — the most advanced version currently in service — that is one of the few weapons capable of shooting down incoming ballistic missiles.

Notably, the purchase is not subsidized or financed by the US, according to the release. Instead, Ukraine is covering the estimated $2.1 billion purchase with funds from Canada, Germany and Norway in addition to a loan from the European Union, the State Department said.