The US has given up on finding the two unidentified flying objects it shot down last week over Alaska and Lake Huron, according to the New York Times.
The search was called off because conditions in the northern areas made tracking down the debris too difficult, the outlet reported on Friday, citing an unnamed US official.
Planes with special radars that can see through the ice were used to look for the downed craft in Alaska, but to no avail, the source said.
Three objects were shot down over Alaska, Lake Huron, and Canada last week, with the Canadian authorities still searching for the debris on their territory, according to the official.
The US launched the hunt for the UFOs after the downing of what it said was a Chinese spy balloon on February 4.
Beijing accused Washington of overreacting, and insisted that the object was a civilian craft mainly used for meteorological purposes, which was blown off course by strong winds.
The row led to the postponement of a visit to China by US Secretary of State Antony Blinken, with Washington imposing sanctions against several Chinese firms and research institutes.
Speaking about the three UFOs on Thursday, US President Joe Biden said that it was unclear what the objects were exactly, but added that there were no grounds to suggest they were surveillance craft from China or any other country.