One day before the rule change was announced, Yanzhong Huang, senior fellow for global health at the Council on Foreign Relations, had called for the abolition of the P.C.R. Travelers from other countries to China, meanwhile, had been allowed to take antigen tests.

The United States, Japan and South Korea no longer require any predeparture tests for travelers arriving from China, but China had not changed its rule until Tuesday. (South Korea had also suspended some visas for Chinese travelers.) China, in response, doubled down on its requirement for travelers from those countries - and suspended the issuing of some visas for Japanese and South Koreans. In January, as the coronavirus spread widely across China, several countries, including the United States, Japan and South Korea, announced mandatory tests for inbound travelers from China. Testing requirements also became politicized. The United States and China have not yet lifted tit-for-tat caps that they imposed on routes between their two countries during the pandemic. International flights remain prohibitively expensive for many, often costing thousands of dollars.

Tourist visas were not reinstated until last month. In practice, the reopening has been slowed, in part, by geopolitical tensions. Beijing has since declared that it is open to the world, and tried to woo foreign businesspeople and diplomats. For three years, China imposed the world’s strictest coronavirus restrictions, requiring lockdowns and regular mass testing in the name of “zero Covid.” Then the government abruptly abandoned those rules in December as the economy sagged, the virus spread widely and protests broke out across the country.

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