The pair of cabinet ministers delivered their announcement not alone, but flanked by about two dozen Conservative caucus members who have ties to Ukraine or represent constituents who do.

"Your comments, your concerns, have been heard," Foreign Affairs Minister John Baird told Ukrainian-Canadians through the cameras. On Tuesday he announced that Canada is barring key Ukrainian officials responsible for what Immigration Minister Chris Alexander called the "repression and silencing" of opposition voices calling for the resignation of the country's president.

The next day and thousands of miles away, Oksana Wynnyckyj ventured into the streets of Lviv, Ukraine, pausing in a city square to watch the news on a big-screen television set up by demonstrators. She was about to walk away when she heard "Canada" in the reports.

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A Canadian living part-time in Ukraine, Ms. Wynnyckyj said she was proud to hear of the government's action and to see the Ukrainian media taking stock of what her home country had to say. "Canada is regarded extremely highly in Ukraine," she said in a telephone interview.

The Ukrainian-Canadian community has long had a voice in Ottawa, and Ottawa listens. While described as cohesive, it does not attach itself to any one political party. But its influence on matters concerning Ukraine was on display on Monday evening, when an emergency House of Commons debate on the crisis there lasted until nearly midnight.

"It's an opportunity for us to have a deciding voice – a leading voice – on one of the top international issues today, punching above our power as a middle-weight," said Chrystia Freeland, a recently elected Ukrainian-Canadian Liberal MP.

Since November, Prime Minister Stephen Harper has met twice with Paul Grod, the president of the Ukrainian Canadian Congress (UCC), most recently on Thursday. The chair of the Canada-Ukraine Parliamentary Friendship Group, Ted Opitz – the Conservative MP who narrowly won Etobicoke Centre, which has a significant Ukrainian-Canadian population – got Mr. Harper's ear on the issue in December.

Mr. Grod accompanied Mr. Baird on a recent trip to Kiev, and met with cabinet ministers on Friday for a roundtable discussion. He said he has "good access" to Mr. Alexander, and called the MP on his cell phone two weeks ago asking him to attend a Toronto rally. Mr. Alexander was there.

This country is home to more than 1.2 million Ukrainian-Canadians, the world's third-largest Ukrainian population behind Ukraine and Russia. The community, built over four waves of immigration dating back at least to 1891, began on the prairies, but more recently has extended into Ontario and Quebec.

The Harper government has made its own connections with the Ukrainian-Canadian community, for example recognizing the Holodomor as an act of genocide, allotting funds for projects acknowledging Canada's internment of Ukrainians during the First World War, and sending hundreds of presidential election observers to Ukraine.

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"Any large diaspora community has influence in Canadian politics, and certainly 1.2 million people is a factor that weighs on the minds of every political leader," said Michael Byers, the Canada research chair in global politics and international law at the University of British Columbia. "But we have to resist the temptation to assume that Canadian foreign policy is all to do with domestic politics."

Besides, he said, members of the diaspora hardly think or vote as a bloc.

Some in the west with farming and labour roots traditionally vote NDP. Some, such as families like that of Etobicoke Centre resident Bob Leshchyshen, embraced the Conservative Party, whose prairie-born leader John Diefenbaker appointed the first Ukrainian-Canadian cabinet minister. There are those who have supported the Liberal Party, such as Etobicoke Centre voter Ms. Wynnyckyj, with some fondly recalling that Pierre Trudeau delivered a speech to the UCC just one day after announcing his multiculturalism policy in 1971.

Ms. Freeland explained that with each wave of immigration, the community has been reinvigorated, with fourth-wave newcomers, for example, teaching the mother tongue to children – including hers – at Ukrainian school on Saturdays. And former Liberal MP Borys Wrzesnewskyj, who lost his seat to Mr. Opitz in 2011, said the community has grown increasingly willing to have a louder, more public voice.

"For centuries, a nail that stuck out got hammered," he said, referring to repression during the Soviet era. "Active engagement is a pretty recent phenomenon. … It's thanks to a new generation."

Ottawa has a long-standing relationship with Ukraine, dating back to 1991, when Canada became the first western nation to recognize Ukraine's independence. Former prime minister Brian Mulroney said then-Soviet leader Mikhail Gorbachev and then-U.S. president George H. W. Bush asked him not to do so, expressing concerns it would be too disruptive. But Mr. Mulroney told his U.S. counterpart, "Sorry, George, but I'm going to do it."

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When asked why he believes Mr. Harper has not yet adopted targeted financial sanctions, as the UCC and opposition MPs such as NDP foreign affairs critic Paul Dewar have advocated, Mr. Mulroney said he is not privy to security briefings and noted: "We don't know what's going on behind the bushes."