President Joe Biden defended his decision to shoot down a Chinese surveillance balloon but promised on Thursday “sharper rules” for handling unidentified aerial objects.

The military is still working to recover the wreckage from three objects shot down in U.S. and Canadian airspace last weekend. Biden said the intelligence community believes they are likely tied to private companies or scientific research, and are unrelated to the Chinese balloon that crossed the country earlier this month and was downed off the coast of South Carolina, where salvage efforts remain underway.

“We don’t have any evidence that there has been a sudden increase in number of objects in the sky,” Biden said. “We’re now just seeing more of them, partially because of the steps we’ve taken.”

The new parameters will be kept classified, Biden said, but will be made available to Congress. They need to remain classified so as to not provide adversaries a roadmap of the United States’ defenses, he said.

“These parameters will guide what actions we’ll take while responding to unmanned and unidentified aerial objects,” Biden said. “We’re going to keep adapting them as the challenges evolve.”

Biden also promised to create an accessible inventory of unmanned aerial objects in U.S. airspace, improve capacity to detect objects that enter U.S. airspace, update rules and regulations for launching and maintaining objects, and work to establish global norms for “this largely unregulated space.”

It remains unclear whether the new parameters — and Biden’s decision to speak publicly about them — will appease lawmakers who have urged the administration to be more transparent about the flying objects. 

Florida Sen. Marco Rubio, the top Republican on the Senate Intelligence Committee, noted during an interview on Fox News Thursday morning that this month’s events mark the first time the U.S. military has shot down an object in American airspace since NORAD, the North American Aerospace Defense Command, was established 65 years ago.

“I do think that merits the president directly addressing why those things were shot down and what we know up to this point,” Rubio commented. “Nothing they’ve talked to us about with regards to those three should be classified, because it’s really not the type of thing you classify.”

During his remarks, Biden also defended his handling of the initial Chinese surveillance balloon. Republicans, and even a handful of Democrats, argued the government should have shot down the balloon before it had the chance to traverse sensitive military sites. 

The Biden administration says it waited until the balloon was over water to protect people and property on the ground and gather its own intelligence on the craft. 

“I make no apologies for taking down that balloon,” Biden said.