WASHINGTON — The Chinese language spy balloon floating over the continental United States generated deep concern on Capitol Hill partially as a result of it got here on the heels of a categorised report back to Congress that outlined incidents of American adversaries doubtlessly utilizing superior know-how to spy on the nation.

The categorised report back to Congress final month mentioned at the least two incidents of a rival energy conducting aerial surveillance with what gave the impression to be unknown cutting-edge know-how, in accordance with U.S. officers. Whereas the report didn’t attribute the incidents to any nation, two American officers accustomed to the analysis mentioned the surveillance in all probability was performed by China.

The report on what the intelligence businesses name unidentified aerial phenomenon targeted on a number of incidents believed to be surveillance. A few of these incidents have concerned balloons, whereas others have concerned quadcopter drones.

The Chinese language authorities mentioned on Friday the Chinese language balloon found this week over america was primarily for climate analysis. Nevertheless, American officers mentioned they’ve assessed it to be a group machine, although not one that would collect the sort of delicate info that superior Chinese language reconnaissance satellites already accumulate.

China spends about $209 billion, or 1.3 p.c of gross home product, on its army total, in accordance with a Pentagon report. However policymakers in Washington have been particularly nervous about its investments in applied sciences that would have army or intelligence functions.

U.S. protection officers imagine China is conducting surveillance of army coaching grounds and workouts as a part of an effort to higher perceive how America trains its pilots and undertakes complicated army operations. The websites the place uncommon surveillance has occurred embody a army base in america and a base abroad, officers mentioned.

Since 2021, the Pentagon has examined 366 incidents that had been initially unexplained and mentioned 163 had been balloons. A handful of these incidents concerned superior surveillance balloons, in accordance with a U.S. official, however none of them had been conducting persistent reconnaissance of the U.S. army bases. (Nevertheless, spy balloons that the U.S. authorities instantly identifies aren’t included within the unidentified aerial phenomenon monitoring, in accordance with two U.S. officers.)

As a result of spy balloons are comparatively fundamental assortment units and different balloons haven’t lingered lengthy over U.S. territory, they beforehand haven’t generated a lot concern with the Pentagon or intelligence businesses, in accordance with two officers.

The surveillance incidents involving superior know-how and described within the categorised report had been doubtlessly extra troubling, involving behaviors and traits that would not be defined.

Officers mentioned that additional investigation was wanted however that the incidents might doubtlessly point out the usage of know-how that was not totally understood or publicly recognized. Of the 171 reviews that haven’t been attributed to balloons, drones or airborne trash, some “seem to have demonstrated uncommon flight traits or efficiency capabilities, and require additional evaluation.”

Officers cautioned that imperfect radar and sensor readings might trigger confusion, making an abnormal object look like one thing threatening.

The Pentagon has launched pictures of among the suspected surveillance incidents that had been initially unexplained. The photographs confirmed inexperienced triangles within the air taken close to two totally different Navy workouts. At a congressional listening to final yr, Pentagon officers mentioned the triangles had been merely small drones. Using night-vision gear had made them look otherworldly.

Whereas the drones had not been formally attributed to any nation, in a single incident a Chinese language ship was within the neighborhood.

It’s not clear how robust the proof is that China is utilizing a sophisticated know-how that america doesn’t possess. Some American officers stay skeptical that China would danger exposing a few of its most superior know-how in any surveillance exercise that may very well be detected by america.

The surveillance balloon stirred outrage on Capitol Hill. Some officers mentioned the details about adversarial spying contained within the categorised report on unidentified aerial phenomena had already pushed up concern earlier.

Each Republicans and Democrats hawkish on China referred to as the surveillance balloon a violation of American sovereignty that highlighted the menace from Beijing.

Consultant Mike Gallagher, Republican of Wisconsin, a member of the Home Intelligence Committee and chairman of a brand new Home committee on China, mentioned the administration wants to inform lawmakers extra about what it is aware of about surveillance of army amenities.

“That is all of the extra cause for the Home Intelligence Committee to obtain a full briefing on this matter,” Mr. Gallagher mentioned Friday. “There’s a documented historical past of unidentified — and now recognized — objects close to delicate army amenities, and we have to transfer with a way of urgency to unravel this.”

When China examined a hypersonic missile in 2021, Gen. Mark A. Milley, the chairman of the Joint Chiefs of Employees, warned that it was one thing near a Sputnik second, referencing the Soviet Union’s profitable Chilly Battle satellite tv for pc launch. Hypersonics has been a key technological focus of Beijing and is one space the place China has demonstrated capabilities equal or exceeding the U.S. army.

However the incidents doubtlessly involving superior know-how described within the categorised report aren’t believed to contain any form of hypersonic propulsion, U.S. officers mentioned.

Helene Cooper and Adam Entous contributed reporting.