Mr. Biden underscored the U.S. commitment to Article 5 of the NATO charter, which spells out that an attack on one member of the alliance must be met with a collective response from all the members.
“We take Article 5 as a sacred commitment, not a throwaway — a sacred commitment that relates to every member of NATO,” Mr. Biden said at a meeting with Polish President Andrjez Duda in Warsaw.
“The single most important criteria in this time of a changing world is that NATO stay absolutely completely united, that there be no separation; that whatever we do, we do in unison,” Mr. Biden said.
“I’m confident that Vladimir Putin was counting on being able to divide NATO and being able to separate the eastern flank from the west, be able to separate nations based on past history, but he hasn’t been able to do it,” Mr. Biden said.
Mr. Duda said the Polish people are feeling a “great sense of threat” right now. He talked about strengthening Poland’s military relationship with the U.S. to boost its defense.
“We are a serious partner, we are a credible ally,” he said. “We do everything we can to live up to the task of defending our country ourselves,” he said.
Mr. Duda talked about how Russia has attacked Poland in the past, saying that his country has begun allocating 3% of its gross domestic product to defense spending. That number is expected to increase over the coming years, he said.
It comes as officials on both sides of the Atlantic warning that a Russian attack on Poland is possible in the near future.
“We do believe that Russian aggression in Ukraine shows a willingness to disregard international borders and to disregard the basic rules of the road of the international community that have been built and sustained over the course of seven decades,” Mr. Sullivan, the White House national security adviser told reporters
Previously, the White House had dismissed questions about whether Mr. Putin would stop with Ukraine as hypotheticals.
But Mr. Sullivan signaled that the U.S. has been preparing for a potential Russian invasion of its Baltic neighbors, including Poland and Romania.
“The president has been very explicit that part of the reason he’s sent forces forward to the Baltic States, to Poland and Romania and he’s supported the setup of these four battle groups southern countries of NATO’s eastern flank is because it is important, in this moment, to send a clear message to Russia that the United States and NATO will defend every inch of NATO territory,” Mr. Sullivan said.
“Against the eastern members of NATO. The Baltic states, Poland — that’s for sure. Will NATO then stop thinking about it, worrying about how Russia will react? Who can be sure of that? And do you have confidence that Article 5 can work?” he said.
Correction: An earlier version of this story incorrectly reported the total number of NATO member countries. There are 30.