More than 15,000 foreign nationals are on Canada's deportation list, but some can't be removed because their home country won't take them back.

The Canada Border Services Agency (CBSA) confirms some countries either delay or refuse to repatriate their citizens who are here illegally, but will not divulge which ones as it might "impact diplomatic negotiations."

"If a country won't take back their foreign nationals, CBSA does not give up; it continues to work with other government partners to put pressure on the country to accept their citizens back," spokesperson Barre Campbell told CBC News in an email.

"The CBSA also works with domestic and international partners to share best practices and develop engagement strategies to address unco-operative countries that fail to repatriate their citizens in a timely matter."

The removal list includes rejected refugee claimants and those deemed inadmissible because of criminal background, potential threat to public health or safety, or risk to national security.

Canada's no-naming approach is in stark contrast to the U.S., which publicly identifies, and in some cases, sanctions, countries that delay or refuse to repatriate their citizens.

Global migration trend

It is one of several countries taking a harder line against resistant countries as the global migration trend continues.

Brian Lee Crowley, managing director of the Macdonald-Laurier Institute, believes Canada should be pushing back hard against nations which aren't "playing by the rules." He said transparency is key to retaining integrity and public confidence in the immigration system.

"If there are specific countries that are refusing to take back their nationals when the government of Canada has determined they're not entitled to stay in Canada, I think the public is entitled to know this and I think the government should be under some public pressure to negotiate with these countries to resolve this problem," he said.

The U.S. had publicly identified 23 countries which either delayed or refused repatriation of their own citizens, but announced earlier this year the list has been shortened to 12 due to public pressure tactics that began under former president Barack Obama and were ramped up under President Donald Trump.

Visa restrictions

It announced that four "recalcitrant" countries, Cambodia, Eritrea, Guinea and Sierra Leone, would face visa restrictions for not accepting, or for delaying, repatriation of their own citizens after the U.S. has tried to deport them.

Others that remain on the U.S. list of unco-operative countries are China, Cuba, Vietnam, Laos, Iran, Myanmar, Morocco, Hong Kong and South Sudan.

Aris Daghighian, an immigration lawyer and executive member of the Canadian Association of Refugee Lawyers, called it "frankly offensive" to name specific countries because it would stigmatize all members of that population.

"That creates the impression that some countries are offloading their unwanted residents on us, and we would more readily get rid of those populations if we could. I think that would be the underlying implication in naming countries that won't take back their residents," he said.

The European Union is also taking steps to deal with resistant countries, including negotiating "readmission" agreements.

In Canada, the number of deportations has declined dramatically in the last five years, from 18,992 in 2012 to 7,364 in 2016. The CBSA did not provide an explanation for the decrease, other than to say there are fluctuations from year to year.

Conservative public safety critic Pierre Paul-Hus said after an enforcement push under the previous Conservative government, removal efforts have eased off due to stretched resources. He is calling on the government to assign more officers to deportation to protect public safety.

Targeting high-risk persons?

But Daghighian said the downward trend could reflect a positive, effective strategy of targeting higher-risk individuals who may be more resource-intensive to track down and remove.

The list of 15,237 foreign nationals currently under orders to leave Canada is topped by Chinese (2,066), Indian (1,029) and American (977) citizens. It includes nationals from 180 countries, as well as 209 stateless persons and 28 whose citizenship is not captured in the CBSA system.

Canada defers or suspends removals to countries where there are systematic human rights abuses, or if there is substantial risk to the entire population due to armed conflict or natural disaster, as is the case for Afghanistan, Iraq and the Democratic Republic of Congo.

Canada's removal numbers are small relative to the U.S., where the Immigration and Customs Enforcement (ICE) carried out 240,255 removals in 2016.

When it comes to deportations from that country, ICE spokesman Brendan Raedy said the U.S. expects other nations to co-operate.

"International law obligates each country to accept the return of its nationals ordered removed from the United States," he said in a statement to CBC News. "The United States itself routinely co-operates with foreign governments in documenting and accepting its citizens when asked, as do the majority of countries in the world."