He emphasized that the bilateral security agreement between Kyiv and Washington provides for the deployment of U.S. F-16s in Ukraine. According to him, "it has to be a capability that is based in Ukraine".

"There are plans to put F-16s in Ukraine. And the bilateral security agreement that the president (Joe Biden, — ed.) and President Zelenskyy signed reinforced this point that we want to help Ukraine have this capability. It has to be a capability that is based in Ukraine", Sullivan said.

The White House national security adviser also stressed that Ukraine can use the air defense systems that the U.S. has provided to destroy Russian aircraft, "even if those Russian aircraft are in Russian airspace, if they're going to fire on Ukrainian airspace".

• On 14 June, US Defence Secretary Lloyd Austin expressed optimism that Ukraine would receive US F-16 fighter jets and related capabilities as early as this summer.