U.S. Secretary of Defense Jim Mattis Thursday announced he was quitting, personally handing his letter of resignation to U.S. President Donald Trump following a lunch meeting at the White House.
While not mentioning Trump by name, the letter from Mattis outlined sharp differences between his views and those of the president, notably on the importance of allies and the use of U.S. power.
“We must be resolute and unambiguous in our approach to those countries whose strategic interests are increasingly in tension with ours,” Mattis wrote, warning that Russia and China in particular "want to shape a world consistent with their authoritarian model-gaining veto authority over other nations' economic, diplomatic and security decisions."
“Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down,” Mattis concluded, saying he would step down at the end of February.
The defense secretary’s decision came one day after Trump announced he would withdraw some 2,000 U.S. troops from Syria, a move the Pentagon opposed.
Mattis did not mention the dispute over Syria in his letter, but he did note his "core belief" that U.S. strength is "inextricably linked" with the nation's alliances with other countries.
President Trump first announced Mattis's departure on Twitter, saying the former four-star Marine general will retire "with distinction."
"During Jim's tenure, tremendous progress has been made, especially with respect to the purchase of new fighting equipment. General Mattis was a great help to me in getting allies and other countries to pay their share of military obligations. A new Secretary of Defense will be named shortly. I greatly thank Jim for his service!"
White House Press Secretary Sarah Sanders told reporters late Thursday that Trump and Mattis are on good terms despite not agreeing on foreign policy and other issues.
"He and the president have a good relationship, but sometimes they disagree," Sanders said. "That doesn't mean you don't have a good relationship with somebody. He was laying out the reasons he was stepping down from his post."
Still, the resignation has sparked an outpouring of anger and despair from both Republican and Democratic lawmakers, and even top U.S. officials.
“I was deeply saddened,” U.S. Director of National Intelligence Dan Coats said in an official statement Friday, describing Mattis as a "national treasure."
"The experience and sound judgement that Secretary Mattis has brought to our decision-making process is invaluable,” Coats continued. “His leadership of our military won the admiration of our troops and respect of our allies and adversaries."
Much of the pushback from U.S. officials and lawmakers has centered on the decision to withdraw U.S. troops from the fight against the Islamic State terror group in Syria – a decision that, according to some officials, ultimately convinced Mattis to resign.
U.S.-backed forces have made steady progress against Islamic State over the past several years. Last week, taking advantage of a dramatic increase in U.S. and coalition airstrikes, the forces were able to enter the town of Hajin, part of the terror group’s last stronghold in eastern Syria.
But despite Trump’s declaration of victory against IS, senior administration officials have said it will be up to the U.S. partner forces to liberate the rest of Hajin and the surrounding areas, where about 2,000 IS fighters have been mounting a stubborn last stand for several months.
Pentagon officials have also warned that despite the gains, IS was still well-positioned to rebuild. And Mattis had said that before leaving, the U.S. must train enough local troops to assume the role of suppressing the militants. He said the United Nations peace process in Syria must progress toward a resolution of the country’s eight-year-old civil war.
While a relatively small number of troops are involved, their withdrawal will have sweeping consequences in Syria's long-running civil war. Allies will be more heavily burdened with confronting energized adversaries and Turkey, Iran and Russia's influence in Syria will increase.
"This is scary," said Senate Intelligence Committee Vice Chairman Mark Warner, a Democrat. "Secretary Mattis has been an island of stability amidst the chaos of the Trump administration."
Republican senator and former presidential hopeful Marco Rubio tweeted, "It makes it abundantly clear that we are headed toward a series of grave policy errors which will endanger our nation, damage our alliances and empower our adversaries."
While the decision to pull out of Syria may have been the last straw for Mattis, tensions have been simmering over other issues for quite some time, including on Russia and Iran.
Mattis believed Russian President Vladimir Putin has been trying to undermine NATO and assaulting Western democracies.
"[Putin's] actions are designed not to challenge our arms at this point, but to undercut and compromise our belief in our ideals," Mattis told U.S. Naval War College graduates at a commencement ceremony in June.
But Trump has praised Putin's leadership skills and recently caused concern among U.S. allies by calling for Russia's reinstatement in the group of major industrial nations. Russia was expelled from what was then the Group of Eight after Moscow's annexation of Crimea from Ukraine.
Another point of contention between the two men involved the Iran nuclear deal.
Mattis argued the U.S. should consider staying in the Iran nuclear deal unless Tehran was found not to be abiding by the agreement. Iran was following the pact's rules, according to the International Atomic Energy Agency, which monitors the use of nuclear energy and has verified Iranian compliance with the accord multiple times since 2015.
Despite Mattis's position, Trump pulled out of the deal in May, saying it had been poorly negotiated during the administration of former President Barack Obama.
As Mattis turned in his resignation, the Defense Department was preparing plans to withdraw up to half of the 14,000 U.S. troops in Afghanistan in the coming months, U.S. officials said. The development marks a sharp departure from the Trump administration's policy to force the Taliban to the negotiating table after more than 17 years of war.
Rumors of Mattis leaving the Defense Department have been circulating for months.
In October, Trump appeared on the television news show 60 Minutes, where he told TV anchor Lesley Stahl that while "I like General Mattis," he believed he knew more about NATO than his defense secretary.
"I think he's sort of a Democrat, if you wanna know the truth," Trump said. "But General Mattis is a good guy. We get along very well. He may leave. I mean, at some point, everybody leaves. Everybody. People leave. That's Washington."
Mattis became secretary of defense shortly after Trump's inauguration and is one of the longest-serving Cabinet members.
Before that, Mattis served 44 years in the Marine Corps and led the Marines and British troops during the bloody Battle of Fallujah in Iraq in 2004.