Mattis has totally flipped on nuclear weapons since the Pentagon decided to take on China and Russia

Associated Press/Manish Swarup

US Defense Secretary Jim Mattis.

• Secretary of Defense Jim Mattis used to question the US's nuclear arsenal and had called for certain elements to be removed or reduced.
• But since joining the Trump administration, Mattis has seemingly reversed his position, and now supports building more.
• Mattis' u-turn suggests he has gained information that nuclear weapons will become important as the Pentagon confronts China and Russia.

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

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

In 2015, Mattis questioned if the US still needed ground-based intercontinental missiles, as he found the risk of accidental launches a bit questionable. When the Senate was confirming him as Trump's Secretary of Defense, Mattis refused to offer his support for a program to update the US's air-launched nuclear cruise missile.

But now Mattis has signed off on a new nuclear position that will not only modernize the ICBMs and cruise missiles, it calls for the creation of two entirely new classes of nuclear weapons. It suggests Mattis learned something about US national security that may have changed his mind.

"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 admission that as secretary of defense, he's come to see harsh realities that changed his position on nukes.

The nuclear posture review, along with a new national defense and national security strategy, have all rolled out in early 2018 and point to a US more focused on combating major powers like Russia and China. Before joining the president, Mattis openly questioned the purpose of US nukes: Do they exist only to deter attacks? Or do they have an offensive value?

The nuclear posture advocated by Mattis now not only calls for an increase in an already massive arsenal, it actually advocates building smaller nuclear weapons to make them more usable in "limited" nuclear conflicts.

Times a-changing

REUTERS/China Daily

Chinese People's Liberation Army Navy recruits chant slogan during a parade to mark the end of a semester at a military base of the North Sea Fleet, in Qingdao, Shandong province December 5, 2013.

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

Now, the US has resolved to go on the offensive against China and Russia by matching their military strength and changing up the rules of engagement. The nuclear posture review advocates using nuclear force against non-nuclear attacks, like massive cyber campaigns on US infrastructure.

Additionally, the review indicates that the US 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 begs the question: What new information did he receive upon joining the Trump team and becoming Secretary of Defense?