WASHINGTON (NewsNation) — President Joe Biden said his administration was acting with an abundance of caution when shooting down three unidentified objects over the past weekend and defended his decision to shoot down a suspected Chinese spy balloon in a press conference on Thursday.

The suspected Chinese spy balloon was shot down on Feb. 4 over the Atlantic Ocean and military divers have been recovering debris to better understand the technology. The incident has heightened tensions between China and the U.S., with China maintaining the balloon was a civilian weather balloon blown off course.

Three additional unexplained objects were shot down from Feb. 10 to Feb. 12, one near Alaska, one over the Yukon Territory in Canada, and one over Lake Huron. All three were described as being smaller than the Feb. 4 balloon, and the exact nature and purpose of the unexplained objects has not been determined.

Biden said the military has adjusted radar parameters to better detect slower-moving objects, such as these objects, and said he acted with an abundance of caution when deciding to shoot down the three unknown objects.

Biden said there is currently no indication that the three objects were linked to China or to any other surveillance projects. He said it is likely they are balloons belonging to private companies for research or other purposes.

“We don’t have any evidence there has been a sudden increase in objects in the sky,” Biden said, adding that the increase in sightings has to do with changes in radar.

Biden said he has instructed his team to develop a concrete set of parameters to deal with such objects going forward and to determine when objects are a security threat.

Biden said his administration will work to develop an inventory of unmanned objects, improve methods to detect unmanned objects in our airspace, establish rules to deal with such objects, and lead a global effort to deal with this emerging issue.

With regard to the Chinese balloon, Biden said he was advised to avoid shooting it down over land because of its size and the potential damage when it hit the ground. He said the military took steps to protect sensitive sites from surveillance before shooting the balloon down safely over water.

Biden said experts are analyzing components recovered from the balloon debris to better understand China’s capabilities.

Biden stressed that he does not seek competition with China, but cooperation, and that there continue to be channels of communication between the two countries. However, he will do what is needed to protect U.S. security.

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

Earlier this week, National Security spokesperson John Kirby said the increase in detected objects was due to adjustments in the radar meant to locate them. As a number of theories have circulated in the public, Kirby also said there was no reason to believe the objects are alien in nature.