Following the announcement, President Volodymyr Zelenskyy tweeted that he had come to the summit in Vilnius, Lithuania, hoping NATO would be an organization that “does not hesitate, does not waste time and does not look back at any aggressor … is that too much to expect?”

On Wednesday, the Ukrainian leader walked back his criticism, saying: “I think by the end of summit, we have great unity from our leaders and the security guarantees — that is a success for this summit, I think so.”

On Sunday, Sullivan acknowledged that while the the alliance fully supports Ukraine, there are conditions the country will need to meet before it can officially become a NATO member, including an end to its war with Russia.

Admitting Ukraine while the war is ongoing would require NATO to join in its defense, Sullivan said.

“Having Ukraine come into NATO while the war is going on would mean that NATO was at war with Russia, it would mean the United States was at war with Russia. And neither NATO nor the United States were prepared to do that,” Sullivan said on ABC’s “This Week.”

Sullivan also noted that every country who enters into the alliance has to make certain democratic reforms.

“Ukraine has made a lot of progress on that pathway. It has more reforms to make,” he said.

“And at the end of the day, President Biden and President Zelenskyy stood together before the world, and President Zelenskyy said that while he didn’t get everything he wanted, he was very satisfied with the results of the NATO summit and very satisfied with the support that he’s getting from his Western partners,” Sullivan added.