Beijing's response to the US shooting down its balloon has been muted. It might be China's way of preparing for a future in which the roles are reversed, says international law expert.

• China has to consider what it will do if the US sends balloons into Chinese airspace, a legal expert said.
• The US shot down what it described as a Chinese "surveillance balloon" on Saturday.

As Beijing calculates its full response to its balloon being shot down off the southeastern US coast on Saturday, it needs to consider what it will do if the US starts sending balloons to China, an international law expert said.

In a statement on Sunday, China condemned the Department of Defense for destroying the balloon, saying the Pentagon "obviously overreacted" and "seriously violated international practices."

But the Foreign Ministry's complaint stopped short of accusing the US of breaking international law, which it often declares if it believes it can argue such a case, Julian Ku, a professor of law at Hofstra University who studies China's role in international law, told The New York Times.

"Moreover, they need to think about their own rights in case the US starts sending balloons or drones into China," Ku told the outlet. "If they push too hard here, it would undermine a future legal argument they might need to make."

It's unclear how long China may choose to dwell on the balloon incident.

So far, its official statement — less than 200 characters — has been muted and unusually brief, compared to how the country has sparred diplomatically with the US in the recent past.

Beijing claims the unmanned balloon was a civilian airship that drifted over American soil by accident, and said it "required the US to handle this properly in a calm, professional, and restrained manner."

The closest it came to a threat was saying that it is "reserving the right to make further necessary actions."

On the other hand, its previous reactions to perceived transgressions — like with then-House Speaker Nancy Pelosi's August visit to Taiwan — have been far more aggressive.

"Those who play with fire will perish by it," China's foreign ministry wrote on August 2 in response to news of Pelosi's trip, warning the US to "not go further down the wrong and dangerous path."

Beijing also responded by conducting live-fire military drills around Taiwan, after it said it would not "sit idly by" if Pelosi landed in Taipei.

"We treat our enemies with fine wine, but for our enemies we got shotguns," China's ambassador to Sweden infamously said on radio in 2019. He'd aired his threats to local authorities when Chinese-born Swedish political publisher and dissenter Michael Gui was awarded the Tucholsky Prize following his 2015 disappearance in Thailand.

Notably, China also now has a new foreign minister, Qin Gang, a former ambassador to the US who in January replaced most of the ministry's top-ranking spokespersons known for Beijing's aggressive "wolf warrior diplomacy."