The news that Secretary of Defense James Mattis would be stepping down was a bombshell Thursday afternoon, but Mattis’ resignation letter makes clear that the decision was not to simply retire, as President Donald Trump attempted to frame it, but a resignation based on fundamental disagreements over policy.

At 5:21 pm ET, Trump posted two tweets noting that Mattis “will be retiring, with distinction” at the end of February, praised Mattis for the “tremendous progress” that had been made regarding “the purchase of new fighting equipment” and in helping him to get “allies and other countries to pay their share of military obligations.”

“I greatly thank Jim for his service!” the tweets cheerfully concluded. That sentiment would not be returned by the retired four-star Marine Corps general.

Mattis’ resignation letter (full text copied below or posted here) expressed pride in accomplishments during his tenure, but not the same ones Trump mentioned. Instead, Mattis listed “putting the Department on a more sound budgetary footing, improving readiness and lethality in our forces, and reforming the Department’s business practices for greater performance.”

More noteworthy, Mattis made clear that he is resigning over policy differences, not simply retiring. “Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects,” he wrote, “I believe it is right for me to step down from my positions.” The resignation comes one day after Trump shocked his advisers and Congress by announcing that the United States would be pulling its troops out of Syria.

The heart of the letter focuses on Mattis’ views regarding how America should strategically work with both our allies and rivals, noting that while he agreed with Trump that “the armed forces of the United States should not be the policeman of the world,” but we are the leader of the free world and “cannot protect our interests or serve that role effectively without maintaining strong alliances and showing respect to those allies.”

Mattis praised “NATO’s 29 democracies” that fought alongside us following the September 11, 2001 terrorist attacks and the “Defeat-ISIS coalition of 74 nations” as “further proof” of the benefits these alliances had for our defense interests — alliances that Trump has publicly belittled, criticizing NATO members as not paying their fair share, among other criticisms.

He then noted the challenges we face regarding countries like China and Russia, which he described as “want[ing] to shape a world consistent with their authoritarian model — gaining veto authority over other nations’ economic, diplomatic, and security decisions — to promote their own interests at the expense of their neighbors, America and our allies.”

“My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues,” wrote Mattis, a sentence that does not require a very deep analysis to view as a rebuke of Trump’s approach to foreign policy and military strategy.

Perhaps most notably — and most likely to spark Trump’s ire — nowhere in the letter does Mattis praise Trump or thank him. Mattis called it a privilege to have held the office and mentioned the men and women of the Department of Defense and who serve in our military, but not the President.

“I very much appreciate this opportunity to serve the nation and our men and women in uniform,” concluded the letter.

Full text of Mattis’ resignation letter, dated December 20, 2018:

I have been privileged to serve as our country’s 26th Secretary of Defense which has allowed me to serve alongside our men and women of the Department in defense of our citizens and our ideals.

I am proud of the process that has been made over the past two years on some of the key goals articulated in our National Defense Strategy: putting the Department on a more sound budgetary footing, improving readiness and lethality in our forces, and reforming the Department’s business practices for greater performance. Our troops continue to provide the capabilities needed to prevail in conflict and sustain strong U.S. global influence.

One core belief I have always held is that our strength as a nation is inextricably linked to the strength of our unique and comprehensive system of alliance and partnerships. While the US remains the indispensable nation in the free world, we cannot protect our interests or serve that role effectively without maintaining strong alliances and showing respect to those allies. Like you, I have said from the beginning that the armed forces of the United States should not be the policeman of the world. Instead, we must use all tools of American power to provide for the common defense, including providing effective leadership to our alliances. NATO’s 29 democracies demonstrated that strength in their commitment to fighting alongside us following the 9-11 attack on America. The Defeat-ISIS coalition of 74 nations is further proof.

Similarly, I believe we must be resolute and unambiguous in our approach to those countries whose strategic interests are increasingly in tension with ours: It is clear that China and Russia, for example, want to shape a world consistent with their authoritarian model — gaining veto authority over other nations’ economic, diplomatic, and security decisions — to promote their own interests at the expense of their neighbors, America and our allies. That is why we must use all the tools of American power to provide for the common defense.

My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues. We must do everything possible to advance an international order that is most conducive to our security, prosperity, and values, and we are strengthened in this effort by the solidarity of our alliances.

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 from my positions. The end date for my tenure is February 28, 2019, a date that should allow sufficient time for a successor to be nominated and confirmed as well as to make sure the Department’s interests are properly articulated and protected at upcoming events to include Congressional posture hearings and the NATO Defense Ministerial meeting in February. Further, that a full transition to a new Secretary of Defense occurs well in advance of the transition of Chairman of the Joint Chiefs of Staff in September in order to ensure stability within the Department.

I pledge my full effort to a smooth transition that ensure the needs and interests of the 2.15 million Service Members and 732.079 DoD civilians receive undistracted attention of the Department at all times so that they can fulfill their critical, round-the-clock missions to protect the American people.

I very much appreciate this opportunity to serve the nation and our men and women in uniform.

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