Justin Trudeau’s cabinet makeover establishes a front line of key cabinet ministers tasked with stickhandling the vital Canada-U.S. relationship in the Donald Trump era.

Job No. 1 for these ministers will be to quickly get to know their counterparts on Team Trump, while seeking common ground on a range of potentially fractious files, including refugees, climate change and the fate of the North American free-trade agreement. They’ll be dealing with individuals who are generally older, more conservative and have much longer government résumés.

Here’s a preview of some of the key matchups, assuming the U.S. Senate confirms all of Mr. Trump’s appointments:

Chrystia Freeland (Foreign Affairs) vs. Rex Tillerson (Secretary of State)

There are hundreds of points of contact in the broad and deep Canada-U.S. relationship. Few are likely to be as important as the dealings between Chrystia Freeland, 48, Canada’s new minister of Foreign Affairs, and Rex Tillerson, 64, Mr. Trump’s nominee for Secretary of State. Their interactions will inevitably span the gamut from Middle East peace and dealing with Russian President Vladimir Putin to NAFTA – files on which they and their respective governments may have divergent views. Ms. Freeland, a former journalist, and Mr. Tillerson, the former head of ExxonMobil, do share an interest in Russia, and geopolitics more broadly. Mr. Tillerson knows Canada well, given ExxonMobil’s extensive operations in Canada. But they are on opposite sides of the debate over sanctions against Russia because of its annexation of Crimea (Ms. Freeland is for them, while Mr. Tillerson has spoken against them). But all of that could pale in importance for Canada on the issue of trade, if Mr. Trump makes good on his threat to renegotiate NAFTA. Tuesday’s cabinet shuffle left Ms. Freeland with primary responsibility for the Canada-U.S. trade file. Meanwhile, a key player in the relationship has yet to be named – Mr. Trump’s pick for ambassador to Canada.

List: Read the full list of who’s in and who’s out of Trudeau’s cabinet

Lawrence Martin: Trudeau cabinet shuffle: Why an overhaul was needed

François-Philippe Champagne (International Trade) vs. Robert Lighthizer (U.S. Trade Representative)

Much of the minutiae of trade will fall to François-Philippe Champagne, 46, and Robert Lighthizer, 69, both trade lawyers turned trade envoys. Mr. Champagne could easily find himself out of his depth on files such as lumber, the troubled Trans-Pacific Partnership, protectionist Buy American rules and trade with China. Mr. Lighthizer is a former top trade negotiator in the Reagan administration and veteran Washington trade lawyer, who has made a career fighting for higher import tariffs and against China’s “mercantilist” trade practices. He’s known as a tough negotiator with a penchant for off-colour language. Mr. Champagne is a government neophyte, elected in the Liberal wave of 2015. The Quebecker spent most of his career overseas as an in-house lawyer for multinationals, first in Zurich, for diversified industrial giant ABB Group, and then in London for Amec Foster Wheeler PLC, an engineering and project-management company. Mr. Champagne will also have to tangle with two other Trump administration trade hawks: Commerce Secretary Wilbur Ross and National Trade Council director Peter Navarro.

Ralph Goodale (Public Security) vs. John Kelly (Department of Homeland Security)

The Trudeau government has one of its steadiest and most experienced ministers on the all-important border file. Ralph Goodale, 67, is a career politician who has held several key federal cabinet posts, including finance. That’s a good thing because Donald Trump is talking about building a wall on the Mexican border, expelling millions of undocumented aliens and cracking down on global terrorism – policies that risk sideswiping Canada. His counterpart will be John Kelly, 66, a tough-talking retired U.S. Marine Corps general who will be Mr. Trump’s wall-builder-in-chief. He has been outspoken on the threat posed by Russia as well as a more balanced approach to protecting borders that doesn’t rely on “goal-line stands.” Mr. Kelly will have the job of running a massive department with a $40-billion (U.S.) budget and 240,000 employees. Created after 9/11, the Department of Homeland Security encompasses antiterrorism, border security, immigration, customs, cybersecurity and disaster response. That will put some cross-border files in the hands of new Immigration Minister Ahmed Hussen, a Somalia-born lawyer and a Muslim.

Catherine McKenna (Environment and Climate Change) vs. Scott Pruitt (Environmental Protection Agency)

Catherine McKenna, 45, is one of the stars of the Trudeau cabinet. She has championed the government’s efforts to combat climate change, including a carbon-tax deal with most provinces. She’ll have her hands full with Oklahoma Attorney-General Scott Pruitt, 48, a climate-change skeptic and staunch oil-and-gas industry ally who led a legal fight against tougher federal environmental rules. As EPA head, he is expected to try to unwind many of President Barack Obama’s efforts to curb greenhouse gases, including tougher regulation of power plants. Also at risk are various cross-border climate-change initiatives struck last year between the Liberal government and the Obama administration, including a joint commitment to cut methane emissions.

Jim Carr (Natural Resources) vs. Rick Perry (Energy Secretary)

Jim Carr, 65, and former Texas governor Rick Perry, 66, might well have more in common than other cross-border counterparts, including a commitment to more oil and gas pipeline capacity in North America, renewable energy and nuclear power. Mr. Perry led a push in Texas to significantly expand wind-energy capacity in recent years. Mr. Carr and Mr. Perry will have to decide what – if anything – to do about the largely dormant Canada-U.S. clean-energy dialogue, launched in 2009 by then-prime minister Stephen Harper and Mr. Obama. The effort was aimed at developing cleaner solutions for energy production, distribution and use. Unlike Mr. Carr’s department, the Department of Energy is not the main U.S. energy regulator. That role belongs to the Environmental Protection Agency. The Department of Energy’s core function relates to nuclear weapons and energy power generation.

Prime Minister Justin Trudeau’s cabinet remake adds more youth, drops more aging white men and brings to the Liberal forefront a new little guy from Shawinigan. The shuffle provides under-performing ministries with some much needed reupholstering. Or so it is hoped. And it readies the Trudeau team – or so it is hoped – for potentially disruptive changes in the continental and world order brought on by the U.S. election of Donald Trump.

The changes to the executive – which are numerous considering the government has only been in power for 15 months – come at a time when the Trudeau ship, despite enjoying high popularity, has been listing. A sense of direction had to be reasserted.

Until new faces are seen in action, no one can say if the cabinet changes are of high quality. But some of the more obvious trouble spots have been attended to. Stéphane Dion, a politician of great integrity, was never a good fit for global affairs. He’s not diplomatic, he’s old school, his English is awkward, he’s stubborn. In the Trump era, more zip and agile thinking is needed.

While not the smoothest performer in front of a microphone for a top diplomat’s job, Chrystia Freeland, the big winner in the shuffle, brings wide-ranging international experience to the post. She has worked in Russia, Britain and New York. She knows Washington, and, having written a book called Plutocrats, she is familiar with the moneyed tycoons she’ll be dealing with on the Trump team.

With protectionist tides rising, the trade portfolio has become a vital one. Into that slot comes a potential new star in the Liberal pantheon. François-Philippe Champagne, who represents Jean Chrétien’s old Quebec riding, is a former engineering company executive who was based in London. The diminutive, 46-year-old, trilingual lawyer was one of 40 people on the planet, along with the likes of actor Leonardo DiCaprio and journalist Anderson Cooper, designated as “a young global leader” by the World Economic Forum in 2009. He’s been serving as parliamentary secretary to Finance Minister Bill Morneau and makes no bones about wanting to follow in Mr. Chrétien’s footsteps.

If there are surprises in the reset, one is that Transport Minister Marc Garneau didn’t get a promotion. He would have been a fine fit for global affairs or trade. But the older generation is not particularly welcome in this new-age Trudeau team. It is a government saddled with tenderfoot Bardish Chagger, 36, in the important role of House leader. A change there would have been welcome. She does not have the heft for the job.

Mr. Trudeau’s shuffle makes a young cabinet even younger and more diversified. Mr. Dion is 61 and joining him on the sidelines is veteran John McCallum, 65, who did good work on refugees in the Immigration portfolio and now moves to a critically important posting as ambassador to China. Moving to Immigration is Ahmed Hussen, 40, the country’s first Somali-Canadian MP. He arrived on these shores alone at age 16 and got a job pumping gas. He became a community organizer, a lawyer and was tagged by a Toronto newspaper in 2004 as a star of the future.

New rookie faces can be fodder for rookie blunders, but obviously Mr. Trudeau doesn’t mind taking such chances. The Democratic Institutions file has been a burden for the Prime Minister since Day One. He’s to blame as much as anyone, because of his brain-hurting changing of signals on how to enact his promised electoral reform. But in the portfolio, Maryam Monsef’s inexperience compounded the stress. Replacing her is another rookie, Burlington, Ont., MP Karina Gould. The Oxford University graduate is only 29, making her one of the youngest Liberal cabinet ministers ever. Moving to the Labour portfolio is Patty Hajdu. In replacing MaryAnn Mihychuk, she does not have a tough act to follow.

In the most important cabinet portfolio – that of Finance – Bill Morneau, as expected, stays put. His coming budget will be more important than anything these new cabinet faces do. The emerging deficit is this government’s trouble spot. To ward off fears of a runaway deficit train, he has to provide target dates for bringing the budget to balance.

加拿大全国性报纸《环球邮报》（The Globe and Mail）发表首席政治评论员克拉克（Campbell Clark）和驻国会记者卡里（Bill Curry）的文章说，十四个月前，总理杜鲁多组成了一个自由党的内阁。现在，他急急忙忙改组，推出了一个应急的内阁。

杜鲁多此举，除了因应加拿大最大贸易伙伴——美国的变局，还想加强和另一大贸易伙伴——中国的经贸关系。由于美国候任总统川普竞选时扬言要废除美国、加拿大、墨西哥三国的“北美自由贸易协定”，可能危及加-美免关税、汽车及汽车零部件贸易、两国过境贸易规则，事关加拿大经济命脉。杜鲁多不得不临阵换将，把国际法专家出身的外交部长迪安解职，由原国际贸易部长方慧兰（Chrystia Freeland）接任外交部长。原因是后者解决了加拿大和欧盟艰难的贸易协议问题，比前者更适合在贸易问题上和川普新政府周旋。

杜鲁多任命的新驻华大使是亲信阁僚——原移民部长麦家廉（Minister of Foreign Affairs, Dean）。麦家廉因此成为第一个出任驻华大使的加拿大政客。他从政前是银行经济学家，现在将肩负拓展加拿大对华贸易的重任。其中包括缔结可能的加-中自由贸易协定。中国通常不是政治任命的加拿大大使的仕途目的地。曾担任驻上海总领事的前加拿大外交官、加拿大亚太基金会主席兼首席执行官贝克（Stewart Beck）认为，派遣像麦家廉这种级别的高官去中国充当杜鲁多的耳目，现在恰逢其时，是颇有灵感的决定。

麦家廉必须平衡两个方面：一是加拿大渴望拓展对外贸易，中国则盼望获得更多加拿大出口的农产品和能源产品；一是民调显示加拿大人对中国国企感到疑虑，并希望渥太华促进外国的人权。麦家廉是资深国会议员，连续六届赢得安大略省万锦市选区（Markham）议席。万锦市是加拿大种族最多元化的社区，聚居着大批华裔加拿大人。麦家廉的妻子南希·林就是华人。

如果说杜鲁多应对川普新政府，为加-美关系可能生变未雨绸缪的是A计划，那么杜鲁多委任麦家廉出使北京，便是加强和另一大贸易伙伴国——中国关系的B计划。中国官员声称，在杜鲁多领导下，“中-加关系出现难得的历史机遇”。杜鲁多把内阁高级阁僚派到中国，显示出他在对华关系上落重注的心态。当然，这种政治任命也符合中国人长期的期盼。