“We are not looking for a new cold war,” Biden said.

Biden, in his most extensive remarks about the Chinese balloon and three unidentified objects downed by US fighters, did not say when he would speak with Xi, but said the United States was continuing to engage diplomatically with China on the issue.

“I expect to be speaking with President Xi, I hope we are going to get to the bottom of this, but I make no apologies for taking down that balloon,” Biden said in response to complaints from Beijing.

After the speech, he told NBC News: “I think the last thing that Xi wants is to fundamentally rip the relationship with the United States and with me.”

China says the 200-foot (60-meter) balloon was for monitoring weather conditions, but Washington says it clearly was a surveillance balloon with a massive undercarriage containing electronics.

Biden, who had made few public comments about the spate of aerial objects that began with the spotting of the Chinese balloon, broke his silence after lawmakers demanded more information on the incidents, which have baffled many Americans.

He said the US intelligence community was still trying to learn more about the three unidentified objects: one that was shot down over Alaska, one over Canada and a third that plunged into Lake Huron. The administration has said they were downed because they posed a threat to civil aviation.

“We don’t yet know exactly what these three objects were, but nothing right now suggests they were related to the Chinese spy balloon program or they were surveillance vehicles from any other country,” Biden said.

The intelligence community believes the objects were “most likely balloons tied to private companies, recreation or research institutions,” Biden said.

Biden said they might have been spotted due to radar that was enhanced in response to the Chinese balloon.

“That’s why I’ve directed my team to come back to me with sharper rules for how we will deal with these unidentified objects moving forward, distinguishing between those that are likely to pose safety and security risks that necessitate action and those that do not,” he said.

Biden said the results of the administration’s review of how to deal with unidentified objects going forward would be classified and shared with relevant members of Congress. “These parameters will remain classified so we don’t give a road map to our enemies to try to evade our defenses,” he said.

Biden’s remarks followed reports that the Chinese balloon, downed on Feb. 4 after crossing the continental United States, originally had a trajectory that would have taken it over Guam and Hawaii but was blown off course by prevailing winds.

The incident prompted US Secretary of State Antony Blinken to postpone a planned February visit to Beijing, where both sides had sought to stabilize already fraught relations.

Blinken’s scheduled attendance at the Munich Security Conference this weekend has raised speculation that he could meet China’s top diplomat Wang Yi there.

The Washington Post reported on Tuesday that US military and intelligence agencies tracked the balloon from when it lifted off from China’s southern island province of Hainan.

It was shot down off the South Carolina coast. American lawmakers have slammed the administration for letting it first drift across the country, including near sensitive military bases.

Asked in advance about Biden’s remarks, a China’s foreign ministry spokesman on Thursday once again referred to the downed balloon as an “unmanned civilian airship,” and said its flight into US airspace was an “isolated” incident.

The US “should be willing to meet China in the middle, manage differences and appropriately handle isolated, unexpected incidents to avoid misunderstandings and misjudgments; and promote the return of US-China relations to a healthy and stable development track,” spokesman Wang Wenbin told reporters at a regular briefing.

Beijing had criticized Washington for overreacting by shooting down the balloon, and warned of “countermeasures against relevant US entities that undermine China’s sovereignty and security.”

On Thursday, China put Lockheed Martin Corp. and a unit of Raytheon Technologies Corp. on an “unreliable entities list” over arms sales to Taiwan, banning them from imports and exports related to China in its latest sanctions against the US companies. Lockheed makes the F-22 Raptor fighter jet that flew the mission to shoot down the Chinese balloon and Raytheon makes the AIM-9X Sidewinder missile that blew it out of the sky.