Why Mattis did an about-face on nuclear weapons

The retired U.S. Marine Corps Gen. Jim Mattis used to doubt the need for the U.S.'s massive stockpile of nuclear weapons, but he has changed his tune since joining President Donald Trump's administration as secretary of defense.

When Trump's team rolled out the Nuclear Posture Review, a report laying out U.S. nuclear policy, Mattis, who vocally opposed expanding or even keeping all of the nuclear arsenal in the past, gave it his blessing.

In 2015, Mattis questioned whether the U.S. still needed ground-based intercontinental ballistic missiles, as he found the risk of accidental launches a bit troubling. When the Senate was confirming him as Trump's secretary of defense, Mattis refused to offer his support for a program to update the U.S.'s air-launched nuclear cruise missile.

But now, Mattis has signed off on a new nuclear position that not only will modernize the ICBMs and cruise missiles but also calls for the creation of two new classes of nuclear weapons.

"We must look reality in the eye and see the world as it is, not as we wish it to be," Mattis wrote in the review, perhaps an acknowledgment that, as secretary of defense, Mattis learned something about U.S. national security that changed his mind.

The nuclear review, rolled out this year along with new national defense and national security strategies, points to a U.S. more focused on combating major powers like Russia and China. Before joining the president, Mattis openly questioned the purpose of U.S. nukes: Do they exist only to deter attacks? Or do they have an offensive value?

The nuclear posture now advocated by Mattis calls for an increase in an already massive arsenal and actually advocates building smaller nuclear weapons to make them more usable in "limited" nuclear conflicts.

Times a-changin'

In the years since 2015, when Mattis spoke of reviewing the U.S.'s 400-some hair-triggered nuclear ICBMs, the world was a different place but starting to change. China was building islands in the South China Sea, and Russia had only just swept into Crimea.

Now the U.S. has resolved to match Chinese and Russian military strength and change up the rules of engagement. The nuclear review advocates using nuclear force against nonnuclear attacks, like massive cyber campaigns targeting U.S. infrastructure.

Also Read: The US is ready to hit North Korea with tactical nukes

Additionally, the review indicates that the U.S. believes Russia is building an underwater nuclear torpedo as a kind of doomsday device.

Mattis has always offered thoughtful answers and pledged to operate on the best information he had on the topic of nuclear weapons, but he has clearly done an about-face since joining the Trump administration.

The abrupt change in Mattis' nuclear posture prompts the question: What new information did he receive upon joining the Trump team?