One of the first issues Donald Trump will be confronted with as he takes office is that of foreign policy, and he must face it strategically, said Richard Haass, president of the Council on Foreign Relations.
"For him, it's both ... a challenge and an opportunity to reassure, in particular, our closest allies in Europe and Asia" of how the United States will conduct its foreign policy under a Trump administration, Haass told CNBC's "Squawk Box."
Haass said foreign powers are already on edge after a tumultuous 18 months of electoral battles between Trump and his Democratic opponent Hillary Clinton. The smart move, he said, would be for Trump to start contacting our allies and laying out his long-term goals.
"What I would begin with is calling your allies. I'd call the British, the French, the Germans, the Japanese, the Koreans, the Israelis, because that's the basis," Haass said.
And, since alliances are "the foundation of American foreign policy," Haass said the key is to remain diplomatic.
"You basically say, 'I look forward to listening to [you], I look forward to working with you, things were said during the campaign, don't overreact,'" Haass said. "Basically, keep an open mind."
But Trump must be careful whom he chooses to call for those preliminary conversations, Haass contended.
Haass also addressed Trump's controversial stance on the Trans-Pacific Partnership, which he saw as more bark than bite.
"On the trade front, more broadly, I think TPP doesn't go anywhere anytime soon," Haass said, noting the bipartisan opposition in Congress to the pact.
More importantly, Haass said, Trump needs to focus on dealings with China — specifically, trade, North Korea and the conflict in South China Sea — and Iran.
The foreign policy expert said a major challenge for Trump will be determining the strength of his Republican support. Many members of the GOP establishment came out against Trump in the last leg of his campaign, which calls into question how much backing the president-elect will be able to pull together when he enters the White House.