Canada’s government revealed on Thursday that China has detained 13 of its citizens since the arrest in Vancouver of Huawei executive Meng Wanzhou last month. Chinese officials subsequently released at least eight of those Canadians.

The two highest-profile Canadians China arrested – former diplomat Michael Kovrig and businessman Michael Spavor – are still in detention. A third Canadian whose arrest was widely reported, teacher Sarah McIver, was released and allowed to return to Canada.

A delegation of Canadian legislators is currently en route to China to discuss the incarceration of Kovrig and Spavor, along with other factors in the strained relationship between Beijing and Ottawa.

Chinese authorities indicated this week they will move ahead with prosecuting Kovrig and Spavor for “activities that undermine China’s national security.” The Washington Post on Thursday quoted experts struggling to read the signals from China, which has been unusually adamant and outspoken about prosecuting the two Canadians, but also seems determined to give them what passes for a fair trial in China, as opposed to the sinister “extralegal” methods it frequently employs in national security cases.

Reuters noted on Thursday that the total number of Canadians detained in China is not terribly large, but the timing of the recent arrests and the sketchy nature of the charges raise suspicions the Chinese are retaliating for the arrest of Meng or amassing leverage to compel her release:

Overall, there are about 200 Canadians who have been detained in China for a variety of alleged infractions who continue to face ongoing legal proceedings. “This number has remained relatively stable,” the official said. In comparison, there are almost 900 Canadians in a similar situation in the United States, the official added. Chinese Foreign Ministry spokesman Lu Kang did not provide details about the other detained Canadians at a news briefing in Beijing on Friday, but said that China was ruled by law and it protected the legal rights of foreigners. The Chinese government has not drawn a direct link between the detention of any Canadian and Meng’s arrest. It has demanded that Canada free Meng and threatened unspecified consequences if it does not.

“We are deeply concerned by the arbitrary detention by Chinese authorities of two Canadians last month,” the office of Canadian Foreign Affairs Minister Chrystia Freeland said on Thursday.

The Canadian ministry has not yet raised the caution level for travelers to China as the U.S. State Department did on Thursday, but the current advisory calls for Canadian travelers to “exercise a high degree of caution.”