Ukraine has to win the war with Russia before becoming a NATO member, U.S. National Security Council spokesperson John Kirby said at a briefing on June 17.
His statement came a few days after Kyiv and Washington signed a 10-year bilateral security deal at the Group of Seven (G7) summit in Italy, recognized as a "bridge to Ukraine's eventual membership in NATO."
"(U.S.) President (Joe Biden) believes firmly that NATO is in Ukraine's future at some point," Kirby said.
In his recent remarks, Biden said that peace in Ukraine means a guarantee that Russia will never occupy the country again, "and it doesn't mean NATO (membership)."
"It means we have a relationship with them like we do with other countries, where we supply weapons so they can defend themselves in the future," Biden added.
There are a lot of things to complete before Ukraine can join the alliance, Kirby said.
"First, they got to win this war. We are doing everything we can to make sure they can do that," he said.
"When the war is over, no matter what it looks like, they still have a long border with Russia and a legitimate security threat to the Ukrainian people."
That is why Biden signed an agreement with his Ukrainian counterpart, Volodymyr Zelensky, to ensure that Kyiv will have what it needs to defend the country for the long haul, Kirby said.
"While they work on the necessary things they have to do like any members of the alliance has to work. For instance, on corruption," he added.
Unlike NATO, the U.S.-Ukraine security deal does not require an American military response if Ukraine is attacked but outlines a long-term defense and other assistance to Kyiv.
Ukraine has voiced hope that NATO's July summit in Washington will bring a more definite signal about Ukraine's future membership in the alliance. American officials made it clear that the country is unlikely to receive an invitation.
Read also: Stoltenberg: NATO fails to agree on long-term financial support for Ukraine