China said it will take countermeasures against American entities that undermine Chinese sovereignty.

That's according to Foreign Ministry spokesman Wang Wenbin at a regular press briefing on Wednesday, after the United States shot down a Chinese balloon off the coast of South Carolina earlier this month and said it would sanction six Chinese companies.

"The US has abused force, overreacted, escalated the situation, and used this as a pretext to illegally sanction Chinese companies and institutions," Wang said.

"China is firmly opposed to this and will take countermeasures against relevant US entities that undermine China's sovereignty and security in accordance with the law."

He said China will resolutely safeguard its national sovereignty and legitimate rights and interests.

Beijing said its balloons are for civilian research purposes. Washington said it suspected they were used for surveillance.

Meanwhile, the US said it has not yet recovered debris from the three most recent objects it shot down, with tough weather conditions making recovery operations difficult.

White House spokesman John Kirby told reporters that no group or individual has claimed the three objects, and that the US intelligence community believes they could be "tied to some commercial or benign purpose."

One object was downed over sea ice near Deadhorse, Alaska; another was brought down over Canada's Yukon; and a third was shot down over Lake Huron. (Reuters)