Ukraine is facing a severe shortage of critical air defence systems as Volodymyr Zelensky has warned that supplies of US-made Patriot missiles have reached a critical low. These systems remain essential for protecting cities from ballistic missile attacks amid ongoing conflict with Russia. Efforts are under way to develop domestic alternatives, but these are not yet operational, leaving Ukraine heavily dependent on international support. Meanwhile, JD Vance has said that ending US military aid to Ukraine is a key policy achievement, increasing pressure on European nations to provide assistance; there were further promises of assistance from them at a meeting in Berlin on 15 April (see). The situation shows how global conflicts and shifting political priorities impact the flow of military resources and support.