By Yashwant Raj Washington, Feb 17 : US President Joe Biden has said that the last three of the four aerial objects shot out of the skies were probably balloons tied to private companies, recreation or research institutions; but the fourth was a Chinese spy and "I make no apologies", he added, for bringing it down. Biden said that he ordered the shooting of the remaining three "due to hazards to civilian commercial air traffic and because we could not rule out the surveillance risk of sensitive facilities". The American President acknowledged that the US knows nothing about these three, which were shot down on consecutive days last week - one over Alaska, the second over Canada in a joint operation with Canada, and the third over the American midwest. Biden said further that he has asked for a new protocol for dealing with these kinds of unidentified aerial objects. The Chinese spy plane, which started this shooting spree, was shot down by a US F-22 on February 4 off the coast of the American state of South Carolina on the western coast. It had been floating above the US mainland for more than a week, hovering over sensitive installations. The Chinese owned up and expressed regret, saying the airship was studying weather and had gone off course. The US declared the aerial intrusion as a violation of its national sovereignty and Secretary of State Antony Blinken postponed his visit to Beijing to express US displeasure more forcefully. Relations worsened as an exchange of sharp words followed, especially after Biden seemingly taunted the Chinese President Xi Jinping in his state of the union speech, saying, no world leader would like to trade places with the Chinese leader because of the spy balloon incident. Biden sounded reconciliatory on Thursday, reiterating that the US doesn't seek a conflict with China and it also doesn't want a new cold war. "This episode underscores the importance of maintaining open lines of communication between our diplomats and our military professionals," Biden said, adding, "Our diplomats will be engaging further, and I will remain in communication with President Xi." /IANS