Romanian Army soldiers deploy a HAWK PIP III R ground-to-air missile launch pad during a joint military exercise with the US Army that aimed to test the interoperability of US and Romanian armed forces in the event of a missile attack, near Corbu village in Constanta county, Romania, November 8, 2016. (Inquam Photos/Ovidiu Micsik/via REUTERS)

The HAWK interceptor missiles would be an upgrade to the Stinger missile systems - a smaller, shorter range air defense system - that the United States has already sent to Ukraine.

The HAWK system is the predecessor to PATRIOT missile defense system which remains off the table for Ukraine, US officials have told Reuters.

US President Joe Biden pledged to Ukraine President Volodomyr Zelenskiy that Washington would provide Ukraine with advanced air systems after a devastating missile barrage from Russia earlier this month.