The Liberal government is being pressed to defend Canadian passport holders as cases multiply of Quebecers being turned away from the U.S. border for mysterious reasons.

But so far, Ottawa has little to reassure travellers nervous about being profiled based on their religion or ethnicity.

On Sunday, Montreal resident Manpreet Kooner was denied entry to the U.S. when she tried to cross into Vermont from Stanstead, Que. She was told she needed a visa, but border agents refused to give her details about what kind.

It is at least the third time in recent weeks that a Canadian citizen who is a visible minority has been blocked from crossing the Vermont border.

Yassine Aber, a 19-year-old University of Sherbrooke student, was turned back at Stanstead last month after being told his travel documents weren't valid. Aber said his Canadian passport expires in 2026.

In early February, Fadwa Alaoui said she was quizzed about her religion and views about U.S. President Donald Trump before guards at the Philipsburg crossing turned her away.

She also holds a valid Canadian passport.

Manpreet Kooner, pictured with her fiancé, was born in Canada and holds a Canadian passport. She claims she was turned away at the U.S. border on the weekend and told she needed an immigrant visa. (Submitted by Manpreet Kooner)

Public Security Minister Ralph Goodale has raised the issue with his American counterpart, U.S. Homeland Security Secretary John Kelly, his office said Monday.

But when questioned, Goodale was unable to offer any guarantees that other Canadians won't face similar treatment when crossing the border.

"Each country has the sovereign right to control their borders," Goodale told reporters outside the House of Commons.

"We also have the high expectation that all of our citizens will be treated respectfully and in a fair manner. "

Call to action

Goodale made similar statements following the incidents involving Aber and Alaoui. On Monday, the NDP expressed impatience at the government's handling of the file.

"They've got to rise up, find the courage, summon the courage within themselves, to stand up and say to President Trump that this is not acceptable," said the party's immigration critic, Jenny Kwan.

The Conservative immigration critic, Tony Clement, described the decision to bar Kooner from entering the U.S. as "absurd and ridiculous."

"I think that what Americans want from their government, presumably, is a government that's focused on bad men and women who are going to do harm to Americans," Clement said. "This lady does not fit that description at all."

The situation also hasn't escaped the notice of Vermont politicians and civil rights activists.

A spokesperson for Vermont Senator Patrick Leahy said the state's congressional caucus — composed of two Democratic senators and one Democratic congressman — is aware of the border-crossing issues and is making inquiries into the matter.

The latest case of a Quebecer being turned away from the border came as the White House unveiled its second attempt at an executive order imposing sweeping travel restrictions on people from Muslim-majority countries.

Within this political context, it is possible border guards feel empowered to make discretionary decisions that violate longstanding human rights principles, said the Vermont branch of the American Civil Liberties Union (ACLU).

"It leaves one to question what is exactly at foot here, and it's not a huge leap to imagine it's discrimination that is at play," said Lia Ernst, a staff attorney at the ACLU's Montpelier office.

White House Press Secretary Sean Spicer posted this photo of U.S. President Donald Trump signing a revised executive order on March 6, 2017, on travel and visas, which now affects six Muslim-majority countries. (Twitter/@PressSec)

Controversial union

The Quebec-Vermont border is patrolled by members of the National Border Patrol Council (NBPC), a union of U.S. Customs and Border Protection officers.

CBC contacted the NBPC for a comment but did not hear back.

During the U.S. presidential campaign, the NBPC publicly backed Trump, a fact he mentioned repeatedly in speeches about his immigration policies. The union's president, Brandon Judd, served on Trump's transition team.

In a 2015 article in a Vermont publication, border agents described the particular challenges that come with patrolling that state's Canadian border.

"The southern border, you don't have to look for aliens; they're practically running you over. Here, you have to be proactive," said Fernando Beltran, who was identified as the agent who runs the border station at Newport, Vermont, just south of Stanstead.

"We get guys coming across, claiming to be from wherever it is, and you're like, That's not even a f--king country. Especially when you get into the 'stans — Uzbekistan. It's, like, 'Man, you're making that up.'"

Uzbekistan is, in fact, a country.