The Chinese balloon that floated over US airspace last week before being shot down by a US military jet Saturday has raised questions of international law on both the US and Chinese sides. The US claims that the balloon was a spy balloon, while China maintains that it was a civilian scientific research balloon that had strayed off course.

On Friday, US Secretary of State Anthony Blinken canceled a planned trip to Beijing. Speaking at a news conference, Blinken said:

It’s very important to emphasize that the presence of this surveillance balloon over the United States, in our skies, is a clear violation of our sovereignty, a clear violation of international law, and is clearly unacceptable, and we’ve made that clear to China. Any country that has its airspace violated in this way, I think, would respond similarly, and I can only imagine what the reaction would be in China if they were on the other end.

Blinken’s statement that the presence of the balloon violated international law, was reiterated by White House spokesperson Karine Jean-Pierre, who said, “it is a clear violation of our sovereignty as well as international law, and this is unacceptable.” Pentagon Press Secretary Brig. Gen. Pat Ryder said, “we do know that the balloon has violated US airspace and international law.”

While Chinese officials have not gone so far as to accuse the US of violating international law by shooting down the balloon, they have accused the US of overreacting. In an official response Sunday, the Ministry of Foreign Affairs said, “Under such circumstances, the US insists on using force, obviously overreacting and seriously violating international practice. China will resolutely safeguard the legitimate rights and interests of relevant companies, while reserving the right to make further necessary reactions.”

On Monday, Ministry of Foreign Affairs spokesperson Mao Ning reiterated this stance:

China is a responsible country that strictly abides by international laws and respects the sovereignty and territorial integrity of other countries. History has proved that it is the United States that often tramples on international law and violates the sovereignty and territorial integrity of other countries. We have already indicated that this is entirely an accidental event caused by force majeure. It is an unacceptable and irresponsible act for the US to deliberately hype up and even attack by force.

It remains to be seen how this incident will impact strained US-China relations.