President Joe Biden said this week that Ukraine is not yet ready to join NATO, calling the prospect of its membership in the international alliance “premature” amid its war with Russia.

“I don’t think it’s ready for membership in NATO,” Biden said in an interview with CNN’s Fareed Zakaria that aired Sunday. “I don’t think there is unanimity in NATO about whether or not to bring Ukraine into the NATO family now, at this moment, in the middle of a war.”

Biden added that Ukraine still has work to do to meet all of the qualifications for membership, cautioning the process is “going to take a while.” But he reiterated his pledge to provide the country with security guarantees in the interim, stressing that the U.S. would ensure Ukraine has the weaponry it needs to defend itself against Russia.

Biden’s vow came shortly after he agreed to send cluster munitions to Ukraine, overriding humanitarian concerns about the bombs by arguing that it was crucial to provide Kyiv with more artillery. The president on Sunday left for an international trip that will include the NATO summit in Lithuania, where he will seek to rally the organization’s support for Ukraine.

“It was a very difficult decision on my part,” Biden said of approving the cluster munitions. “But the main thing is, they either have the weapons to stop the Russians now from their — keep them from stopping the Ukrainian offensive through these areas, or they don’t. And I think they needed them.”

Biden during the interview also expressed optimism that Sweden would soon gain entry to NATO, and touted the alliance’s ability to remain united in the face of Russia’s invasion of Ukraine.

“I believe Putin has had an overwhelming objective from the time he launched 185,000 troops into Ukraine, and that was to break NATO,” he said. “So holding NATO together is really critical.”

During the wide-ranging discussion, Biden also was asked about the White House’s posture toward China. The president said he was confident the U.S. could reach a “stable point” with its international rival and would work toward establishing a “working relationship with China that benefits them and us.” But he also indicated he believes that China’s overarching goal is to become the largest economic and military power in the world.

“China has enormous potential capacity, but enormous problems as well,” he said. “I think there’s a way we can work through this.”

Biden warned Chinese President Xi Jinping against providing more support to Russia in its war against Ukraine, he added, emphasizing the economic blow if American corporations pulled out of the nation at the same pace as they have in Russia.

“I said, this is not a threat, this is an observation,” Biden said. “And if you notice, he has not gone full-bore on Russia.”

Biden also waved away questions about his age amid concerns over the ability for an 81-year-old seeking reelection to excite the Democratic base ahead of the 2024 election, arguing that he possesses “wisdom” only gained through his decades in politics.

“We’re uniting democracies,” he said, pointing to the continued support for Ukraine across Europe. “I think we have enormous opportunities. And I just want to finish the job, and I think we can do that in the next six years.”