The Chinese spy balloon that flew across the U.S. earlier this year was able to gather intelligence from several sensitive American military sites, despite the Biden administration’s efforts to block it from doing so, according to two current senior U.S. officials and one former senior administration official.

China was able to control the balloon so it could make multiple passes over some of the sites (at times flying figure-eight formations) and transmit the information it collected back to Beijing in real time, the three officials said. The intelligence China collected was mostly from electronic signals, which can be picked up from weapons systems or include communications from base personnel, rather than images, NBC reported.

Officials said China could have gathered much more intelligence from sensitive sites if not for the administration’s efforts to move around potential targets and obscure the balloon’s ability to pick up their electronic signals by stopping them from broadcasting or emitting signals.

China has said repeatedly that the balloon was an unmanned civilian airship that accidentally strayed off course, and that the U.S. overreacted by shooting it down.

The balloon entered U.S. airspace over Alaska on Jan. 28, according to the Biden administration, which said it was tracking it as it moved. Within the next four days, the balloon was flying over Montana — specifically Malmstrom Air Force Base, where the U.S. stores some of its nuclear assets.

Once the balloon’s existence became public, China increased its speed, officials said, in an attempt to get it out of U.S. airspace as quickly as possible, NBC reported.

The U.S. shot down the balloon on Feb. 4 off the coast of South Carolina, and officials are still analyzing the debris that was retrieved.