While the Biden administration said there was no deal tying the resolution of Ms. Meng’s case to the release of the siblings, their prolonged detention in China appeared to be related to Ms. Meng’s arrest in December 2018, said Evan Medeiros, a professor at Georgetown University who was senior Asia director at the National Security Council under President Barack Obama.
In late 2018, President Donald J. Trump had raised the issue of Mr. and Ms. Liu’s release at a summit in Argentina with President Xi Jinping of China, and Mr. Xi had agreed to let them leave, said Mr. Medeiros, who was involved in efforts to release the siblings. But on the day the summit ended, Ms. Meng was taken into custody in Canada, and the agreement was off.
“There appears to have been a de facto linkage for China,” Mr. Medeiros said in a telephone interview.
American officials have repeatedly warned that exit bans of U.S. citizens were a major concern. In its advisory for American citizens thinking of going to China, the State Department singles them out as a risk. Often people find out that they are blocked only when they try to leave, states the advisory, “and there is no reliable mechanism or legal process to find out how long the ban might continue or to contest it in a court of law.”
Secretary of State Antony J. Blinken pressed senior Chinese officials about exit bans during talks in Anchorage in March, and raised cases of Americans trapped in exit bans during a phone call with China’s top foreign policy official, Yang Jiechi, in June.
When the deputy secretary of state, Wendy R. Sherman, visited China for talks in July, she “raised the cases of American and Canadian citizens” detained in China or held under exit bans, and told Chinese officials that “people are not bargaining chips,” the State Department said at the time.
Last month, Ms. Sherman held a meeting in Washington with China’s recently arrived ambassador to the United States, Qin Gang, and “reviewed issues” from her earlier talks in China, the State Department said.