Jim Mattis has announced his resignation citing policy differences with his president. He was seen as a stabilizing force for international order in the chaotic, go-it-alone administration.
US Secretary of Defense Jim Mattis will step down at the end of February, he announced in a letter to US President Donald Trump. Trump tweeted the news on Thursday, saying Mattis was "retiring, with distinction, at the end of February."
The retired Marine Corps four-star general was regarded as a stabilizing figure in Trump's often-changing Cabinet. The Trump administration has had the highest senior-level staff turnover of the past five presidents, according to the Brookings Institution.
In a letter announcing his resignation, Mattis said it was his core belief that the US needs to maintain strong alliances and show respect for allies. He wrote that the US needs to be "unambiguous" with nations such as Russia and China.
"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," he wrote. "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 by the solidarity of our alliances."
He then said part of the reason he was stepping down to make way for a defense chief whose views aligned more closely with those of the president.
Fears of instability
Trump said he would name Mattis' successor soon.
NATO responded to the news by praising Mattis' contribution to the alliance, while also expressing gratitude for what it called "the iron-clad commitment of the United States to NATO," despite this commitment having been called into question in past comments by Trump.
Republican Senator Marco Rubio was one of several senators to lament his departure.
"Just read Gen. Mattis resignation letter," he said on Twitter. "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."
"This is scary," Senate Intelligence Committee Vice Chairman Mark Warner said on Twitter. "Secretary Mattis has been an island of stability amidst the chaos of the Trump administration."