The U.S. military said Monday it discovered important electronic parts of a suspected Chinese spy balloon shot down by a U.S. fighter jet off the coast of South Carolina on Feb. 4, including sensors allegedly used to gather intelligence, the Voice of America reported.

The Chinese blimp, allegedly intended to gather intelligence - Beijing denies this - was in the skies over Canada and the United States for a week before President Joe Biden ordered its downing. The episode strained relations between Washington and Beijing, causing Secretary of State Anthony Blinken to postpone a trip to China.

It also led the U.S. military to begin intensely checking the skies for other targets that had not been captured by radar, leading to an unprecedented three shoot-downs between Friday and Sunday.

The military and the Biden administration acknowledged that much about the latest unmanned objects remains unknown, including how they are kept in the air, who built them and whether they may have been gathering intelligence.

On Monday, Defense Secretary Lloyd Austin tried to reassure Americans about the risks posed by unidentified objects.

The U.S. military said the follow-on flying objects were more difficult to shoot down than the Chinese balloon, given the smaller size and the objects' lack of radio signals.

Austin said the U.S. military has not yet recovered any debris from the last three downed objects, one of which went down off the coast of Alaska. Another object was shot down over the Yukon in Canada.

U.S. officials have refused to link the incidents.

However, Canadian Prime Minister Justin Trudeau said Monday that the four aerial objects shot down in recent days are somehow connected, without going into detail.