United States President Joe Biden says the three mysterious objects shot down by US fighter jets over North America do not appear to have been used for spying. They are also likely not linked to China's spy balloon program — but there are limited theories as to what they actually were. Here's what we know. What does the United States think the objects were? Recovery efforts are still underway, but US officials have so far labelled the three objects as likely "benign" and "not nefarious". Mr Biden said on Wednesday local time: “We don’t yet know exactly what these three…