Tillerson, 64, got his start as a production engineer at Exxon in 1975 and has worked there ever since, running business units in Yemen, Thailand and Russia before being named chief executive in 2006. He was expected to retire next year.

Critics suggested that if President-elect Donald Trump were to choose Tillerson – as a source familiar with the situation said he was expected to do – it would continue a trend of selecting some aides who may favor a softer line toward Moscow.

Among these is Trump’s pick for national security adviser, Michael Flynn, who raised eyebrows when he sat beside Russian President Vladimir Putin at a Moscow banquet last year and who has argued that the United States and Russia should collaborate to end Syria’s civil war and to defeat Islamic State militants.

Some former officials said it was an open question whether Tillerson could make the transition from running Exxon, a vast company that explores for oil and gas on six continents, to the even greater complexity of being secretary of state.

Meet Exxon Mobil’s CEO, Rex Tillerson

“Negotiating a real estate deal or an oil contract with Saudi Arabia is not the same thing,” said Aaron David Miller, a former State Department Middle East specialist now at the Wilson Center think-tank in Washington.

“It’s not a complicated summit where you are trying to reconcile historical woundings, religious identities, sectarian tensions.”

“I’m not arguing that he can’t make this conversion. I just don’t think we know.”

‘A STRAIGHT ARROW’?

Many U.S. officials are worried by Russia’s increasingly aggressive behavior. It annexed Crimea from Ukraine in 2014, has supported Syrian President Bashar al-Assad in the Syrian civil war and is accused of interfering in U.S. domestic politics.

U.S. intelligence analysts have concluded that Russia intervened in the 2016 election to help Trump defeat Hillary Clinton, and not just to undermine confidence in the U.S. electoral system, a senior U.S. official said.

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In his role at Exxon Tillerson maintained close ties with Putin and opposed U.S. sanctions against Russia for its incursion into Crimea.

Daniel Yergin, author of the Pulitzer Prize-winning The Prize: the Epic Quest for Oil, Money, and Power, said Russia represented a relatively small portion of Exxon’s overall operations and played down its significance.

“It was a business relationship,” Yergin said.

“The whole Russian thing is so much front and center now so it’s inevitable that those questions be asked but, obviously, if you are a major oil company, you want to go to where your resources (are). You have to replace your reserves,” he added.

“If he becomes secretary of state, the interests he will pursue will be U.S. interests. This is an Eagle Scout kind of guy. He was president of the Boy Scouts,” he said. “He is a straight arrow. If that’s his mission, that’s what he’ll do.”

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In an interview to be aired on Fox News Sunday, Trump praised Tillerson as “much more than a business executive.”

“He’s a world class player,” Trump said. “To me, a great advantage is he knows many of the players, and he knows them well.”

However, Senator Robert Menendez of New Jersey, a senior Democratic member of the Senate Foreign Relations Committee that would weigh Tillerson’s nomination, was unsparing in his criticism of the possible appointment.

“Reports that Rex Tillerson could be nominated to be our nation’s top diplomat (are) alarming and absurd,” he said. “With Rex Tillerson as our secretary of state the Trump administration would be guaranteeing Russia has a willing accomplice in the president’s cabinet guiding our nation’s foreign policy.”

Should Tillerson be nominated, climate change could be another controversial issue.

Exxon is under investigation by the New York Attorney General’s Office for allegedly misleading investors, regulators and the public on what it knew about global warming.

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However, if chosen, Tillerson would be one of the few people selected for major roles in the Trump administration to believe that human activity causes climate change.

After Trump’s election, Exxon came out in support of the Paris Climate Agreement. It has also advocated for a carbon tax and internally factors in a theoretical price on carbon as it weights manufacturing and exploration costs of projects.

Some environmental groups are alarmed at the prospect of Exxon’s CEO as the country’s top diplomat.

“Donald Trump appears intent to undo a century of environmental and social progress and return America to the age of robber barons and corporate trusts,” said Carroll Muffett, president of the Center for International Environmental Law.

“Who better to turn to than Exxon, the granddaddy of them all?”