A high-profile group of think tank leaders and scholars is calling for the release of a Canadian policy adviser being held in China, warning that his detention threatens U.S.-China relations at a critical moment. 

In a rare joint statement published Monday, leaders working for top U.S. and international institutions said the arrest of Michael Kovrig of the International Crisis Group on vague allegations of endangering national security is having a “chilling effect” on efforts to improve the bilateral relationship.

The statement comes more than three months after Kovrig was detained in China in apparent retaliation for the arrest in Vancouver of Chinese technology executive Meng Wanzhou. The United States and its allies have said Kovrig’s detention is unlawful and have called for his immediate release. 

It also comes as the United States and China remain locked in a tense dispute over trade, technology and other issues — a dispute that the signatories worry will deepen if independent policy institutions are no longer able or willing to conduct research in China. 

“At this moment of testing for the bilateral relationship — defined by growing differences and suspicions between our governments — we believe these efforts and the partnerships we’ve built with counterparts in China over many years are more important than ever,” the statement said.

“Michael’s arrest has a chilling effect on all those who are committed to advance constructive U.S.-China relations. We urge China to release Michael so that he can return to his family.”

The statement is a show of unity and resolve from U.S. think tanks and academic leaders across the political spectrum. Signatories include senior leaders from the Brookings Institution, the American Enterprise Institute, the Carnegie Endowment for International Peace and the Hudson Institute, as well as former diplomats such as Anne-Marie Slaughter and Nicholas Burns. 

“Canada appreciates the efforts by this group of leading international organizations to speak publicly in support of a Canadian citizen,” Adam Austen, a spokesman for Canadian Foreign Minister Chrystia Freeland, said in an email to The Washington Post.

“We would also like to express our appreciation to all those who have spoken in support of these detained Canadians and the rule of law to date. This includes Australia, the EU, France, Germany, the United Kingdom, the United States, the Netherlands, Latvia, Lithuania, Estonia, Spain, the Czech Republic, Denmark, NATO, and a bipartisan group of US Senators.

In January, a group of more than 200 academics and former diplomats signed a letter calling for Kovrig and another Canadian, businessman Michael Spavor, to be released. 

The letter warned that researchers were getting nervous about traveling to China.

“We who share Kovrig and Spavor’s enthusiasm for building genuine, productive, and lasting relationships must now be more cautious about traveling and working in China and engaging our Chinese counterparts,” it said.

The arrests are part of a complicated conflict that has put Canada in the middle of a broader standoff between the United States and China. 

Kovrig is a former diplomat who had worked since 2017 as an adviser for the Brussels-based International Crisis Group, conducting research on northeast Asia, including China, Japan and the Koreas.

He was detained in December in a move that is widely considered retaliation for the arrest of Meng, chief financial officer for Huawei Technologies, who was wanted on U.S. charges. 

Meng was arrested at Vancouver’s airport on Dec. 1. As China scrambled to secure her release, Chinese authorities detained Kovrig and, later, Spavor.

Not long after, Robert Lloyd Schellenberg, a Canadian serving time in China for smuggling drugs, was hastily retried and sentenced to death. 

As Meng awaits her extradition hearing from the comfort of one of her family’s multimillion-dollar houses in Vancouver , Kovrig and Spavor are being held without charge and with no access to lawyers.

The International Crisis Group thanked colleagues for urging Kovrig’s release.

“We are extremely grateful and heartened by the support shown by the prominent signatories from the research community and by the fact that they have come together as one on this issue,” said Robert Malley, the organization’s president and chief executive.

“Many members of that community wish to constructively engage with China. Michael’s arbitrary detention can only scare them away.”