The United States has approved the sale of 500 Patriot missiles to Ukraine, a critically-needed munition for defence against escalating Russian aerial attacks. However Ukrainian President Volodymyr Zelensky has warned it could take "several years" for the deliveries to arrive. The US State Department said the advanced PAC-3 interceptor missiles would cost $2.1bn (1.6bn) and would be "funded entirely" by Kyiv's allies in Europe and Canada.