President Barack Obama’s outgoing envoy to Canada has some guidance for Prime Minister Justin Trudeau in dealing with the new Trump administration: Don’t assume anything. “If I was going to give one piece of advice,” U.S. Ambassador Bruce Heyman said in an interview with Bloomberg, it would be that “whenever you are working on a relationship that’s new, don’t presume that the other party really understands all the history and background as to where you are.” “Take a bit of time to explain the relationship,” he said. Heyman, a former Goldman Sachs banker whose term ends this week along with Obama’s presidency, departs Ottawa with the relationship between the two countries at its warmest point in almost a decade. While the bond has been cemented by strong personal ties and parallel agendas between Obama and Trudeau, there are many questions in Canada about what lies ahead when Donald Trump becomes president. Though Heyman declined to comment on the transition, he commended Trudeau’s efforts to reach out to the new Trump administration and set a collaborative tone. Trudeau has confirmed that senior aides and Canada’s ambassador to Washington have held talks with the president-elect’s team. “The work that they’ve been doing here recently and reaching out to the new administration and the tone and the style in which he’s approaching this is I think the right path,” Heyman said. “From my perspective, there is no more important country in the world for the United States than Canada. None. ” Economic Bond For one, Heyman said, the U.S. economy is dependent on a “successful Canada.” The U.S. has a trade surplus with Canada once oil and gas is excluded, he said, and Canada is also the No. 1 export market for the U.S. “Canada creates U.S. jobs,” he said. When Heyman, an Obama fundraiser who was nominated to the post in 2013 after a 33-year career at Goldman Sachs, began his tenure, relations were dominated by TransCanada Corp.’s controversial Keystone XL pipeline under Trudeau’s predecessor, Stephen Harper. Trudeau—who broadened the bilateral conversation, particularly toward climate change—had repeatedly blamed Harper’s aggressive and single-minded pursuit of a cross-border energy project for a fractious relationship with the White House. While Obama would reject Keystone only three days into Trudeau’s government, the relationship hasn’t suffered. Among the list of achievements was a coordinated ban of new offshore oil and gas drilling in the Arctic, a state visit to Washington for Trudeau, a North American leaders summit in Canada and a climate-change agreement. Personal Ties “I will tell you I’ve never seen in business or otherwise two people get along and be more simpatico as Prime Minister Trudeau is with President Obama,” Heyman said. “As a result of that, we were able to affect a lot of things that happened that hadn’t happened in a long time.” Heyman argues that even the energy relationship between the two countries hasn’t suffered, citing Canada’s growing market share of U.S. energy imports. “We’re importing more from Canada at a time when we are importing less from around the world,” Heyman said. “Canada’s market share increased substantially during the Obama administration, so people miss that.” With Obama’s departure, Trudeau is also becoming one of the main standard-bearers for liberalism globally. Or as Vice-President Joe Biden said in a visit to Ottawa last month: “The world’s going to spend a lot of time looking to you, prime minister, as we see more and more challenges to the liberal international order since the end of World War II—you and Angela Merkel.” ‘Huge Opportunity’ One question is how Trudeau’s agenda—pro-environment, pro-trade and extremely progressive on social issues—plays with the Trump administration and the Republican-dominated House. Another is what becomes of the North American Free Trade Agreement, which the president-elect has vowed to renegotiate. According to Heyman, Trudeau’s progressive stance on social issues remains a “huge opportunity” to deepen Canada’s relationship with the U.S., not a hindrance. Trudeau “has a very important voice right now in the world with regard to this leadership,” Heyman said, adding that “core progressive social values” run across party lines in Canada. “The president has told him that.” “I’m not overly concerned about that creating an issue with the U.S.-Canada relationship,” Heyman said. “There are a lot of Americans who share very similar ideals. Millions.”