Sport is a serious business. Ping-pong diplomacy sped US detente with China; Richard Nixon followed the path of American table tennis players. Now some joke that basketball could yet spell the end for bilateral relations, as Beijing seeks to punish the NBA over comments on the protests in Hong Kong and US politicians hit back at the league’s attempts to appease.

China’s use of economic power for political purposes has rarely been quite so visible. It began when the general manager of the Houston Rockets sent a tweet including the words “Fight for Freedom. Stand with Hong Kong” – where authorities are cracking down harder than ever on the four-month anti-government movement and violence is growing. The team’s Chinese sponsors and partners cut ties. Matters soon spiralled.

China is the NBA’s biggest market outside of its homeland; its business there has been estimated to be worth as much as $4bn. The NBA said it was regrettable that the remarks had deeply offended many people in China. The Chinese version went further, suggesting the league was “extremely disappointed” by an “inappropriate” comment. The commissioner, Adam Silver, then issued a statement insisting the NBA would not regulate what players, employees or team owners said. The league succeeded in satisfying no one.

This is not an independent consumer boycott. The party-state zealously fosters and directs nationalism, and in this case its intervention is not only direct but open. The state broadcaster scrapped its plans to air pre-season games played in China this week. Similarly, Apple’s decision to remove an app tracking the movement of Hong Kong police from its store came after a state-owned Chinese paper accused it of “protecting rioters” with its “poisonous app” (the company, citing officials, says it has been used to ambush police).

Others are acting pre-emptively: Blizzard Entertainment expelled a victorious Hong Kong-based gamer from a tournament after he spoke in support of the protests. Self-censorship by western businesses under pressure is nothing new. China is exporting its controls on speech. Hollywood, car manufacturers, airlines, internet companies and hotel chains have already learned to accept – or pay a hefty price. But giving ground encourages Beijing to demand more. Just how narrowly it sets the parameters of acceptable discussion was spelt out this week by state media, which warned that “any speech that challenges national sovereignty and social stability is not within the scope of freedom of speech”. (In fact, very few in Hong Kong call for independence, and “social stability” is an almost all-encompassing rubric.)

China’s increasingly strident nationalism and confidence, combined with its immense economic clout, make more clashes inevitable. The NBA’s high profile makes it a tempting target; its punishment has a clear chilling effect. But its status also means that the row has highlighted Beijing’s tactics, and spurred a backlash – as well as refocusing international attention on Hong Kong. Ted Cruz and Alexandria Ocasio-Cortez found a rare moment of political unity when they co-signed a bipartisan letter urging the league to suspend activities in China until the pressure ceases. Western businesses concluded long ago that they cannot afford to stay out of the Chinese market. But domestic consumers and politicians still have power. They should remind companies that failing to uphold values such as free speech at home also comes at a cost.