When US President Joe Biden learned a suspected Chinese spy balloon was drifting through the stratosphere 60,000 feet above Montana, his first inclination was to take it down.

By then, however, it was both too early and too late. After flying over swaths of sparsely populated land, it was now projected to keep drifting over American cities and towns. The debris from the balloon could endanger lives on the ground, his top military brass told him.

Its arrival had gone unnoticed by the public as it floated eastward over Alaska – where it was first detected by North American Aerospace Defense Command on January 28 – toward Canada. NORAD continued to track and assess the balloon’s path and activities, but military officials assigned little importance to the intrusion into American airspace, having often witnessed Chinese spy balloons slip into the skies above the United States. At the time, the balloon was not assessed to be an intelligence risk or physical threat, officials say.

This time, however, the balloon kept going: high over Alaska, into Canada and back toward the US, attracting little attention from anyone looking up from the ground.

It would take seven days from when the balloon first entered US airspace before an F-22 fighter jet fired a heat-seeking missile into the balloon on the opposite end of the country, sending its equipment and machinery tumbling into the Atlantic Ocean.

The balloon’s week-long American journey, from the remote Aleutian Islands to the Carolina coast, left a wake of shattered diplomacy, furious reprisals from Biden’s political rivals and a preview of a new era of escalating military strain between the world’s two largest economies.

It’s also raised questions about why it wasn’t shot down sooner and what information, if any, it scooped up along its path.

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