The U.S. military said on Sunday it was searching for remnants of the suspected Chinese surveillance balloon it shot down a day earlier, while Beijing urged Washington on Monday not to escalate the issue or take further action to harm its interests.
The drama over the balloon, which Beijing again reiterated was a civilian airship that accidentally strayed into U.S. airspace, has further strained tense relations, prompting Washington to cancel a planned visit to Beijing by Secretary of State Antony Blinken.
A successful recovery could potentially give the United States insight into China's spying capabilities, though U.S. officials have downplayed the balloon's impact on national security.
A U.S. fighter jet shot down the balloon in the Atlantic off South Carolina on Saturday, a response China described as an "obvious overreaction".
China has said the balloon, intended for meteorological and other scientific purposes, had accidentally blown off course.
"China firmly opposes and strongly protests against this," Vice Foreign Minister Xie Feng said in remarks to the U.S. embassy in Beijing posted on the ministry's website on Monday.
"The Chinese government is closely following the development of the situation," he said.
Later on Monday, foreign ministry spokesperson Mao Ning said China had found out its balloon had drifted over the United States after being notified by that country.
She said another balloon, sighted in Latin America, was from China and intended for civilian purposes.
On Sunday, Colombia's military said it sighted an airborne object similar to a balloon, after the Pentagon said on Friday that another Chinese balloon was flying over Latin America.
The balloon incident comes as the United States and China have sought to bolster communications and begin to mend ties that had been under severe strain in recent years over tensions on several fronts, including U.S. efforts to block Chinese access to key cutting-edge technologies.
China has warned of "serious repercussions" and said it will use the necessary means to deal with "similar situations", without elaborating, although some analysts said they expect any response to be finely calibrated to keep from making bilateral ties even worse.
Brokerage ING said in a Monday note that the incident could exacerbate the "tech war" and would have negative near-term impact on China's yuan currency.
"Both sides will likely impose more export bans on technology in different industries. This is a new threat to supply chain disruption, although the risk of logistical disruption from Covid restrictions has now disappeared," it said.
"This new risk is more of a long-term risk than an imminent one," ING said.
China's yuan rebounded on Monday after falling to a low of 6.8077 against the dollar in early trade, for its weakest level in nearly a month.