"There are countries that have Patriots, and so what we're doing is continuing to engage those countries," Austin told a House Armed Services Committee hearing.

"I have talked to the leaders of several countries... myself here in the last two weeks, encouraging them to give up more capability or provide more capability," he said, without identifying the countries by name.

Various European Union countries possess the systems, including Spain, Greece, Germany, the Netherlands, Poland and Sweden.

Ukrainian President Volodymyr Zelensky told NATO members earlier this month that his country needed a minimum of seven additional Patriot or other high-end air defense systems to counter Russian air strikes, urging them to step up their military assistance for Kyiv.