Defense Secretary Mattis won't say what a US aircraft carrier is up to near North Korea

Defense Secretary Jim Mattis explained Tuesday the decision to strike Sharyat air base in Syria with 57 cruise missiles, and noticeably seemed to avoid a looming nuclear threat — North Korea. 

The USS Carl Vinson aircraft carrier and strike group have been deployed to the Korean peninsula in response to North Korea's nuclear threats, which prompted the Kim regime to warn the US of potential nuclear strikes should they be provoked.
But according to Mattis, there's nothing to make of the carrier strike group redirecting itself to the region.
"She's stationed there in the western Pacific for a reason. She operates freely up and down the Pacific," said Mattis of the Vinson, implying the imposing carrier would send a message to North Korea and other actors in the region.
However, when pressed on what exactly that reason might be, Mattis seemed to backtrack saying "there's not a specific reason or demand signal," that brought the Vinson to the Korean peninsula.

North Korea's Kim regime, which US presidents have tried for decades to engage with diplomatically, has recently stepped into a visible and distressing stage of its nuclear and ballistic missile program that requires testing.

Experts have told Business Insider that once North Korea perfects an intercontinental ballistic missile, it reaches a "point of no return" whereby the US no longer has any military credibility against the Kim regime and may be forced to acknowledge it as a national power. 

The US has repeatedly and openly mulled military action against the Kim regime, but Joel Wit, co-founder of 38 North, a website that brings together experts on North Korea, told Business Insider that "it's almost universal that the downsides of military strikes are so great that it's hard to see them taking place."

North Korea's nuclear and conventional forces are too spread out to wipe out all at once. Additionally, their artillery installations and missile launchers could likely level Seoul, South Korea's capital city and home to 10 million people.

Trump reiterated in a tweet on Tuesday that "North Korea is looking for trouble. If China decides to help, that would be great. If not, we will solve the problem without them!" also adding that he told Chinese President Xi Jinping at their meeting on Thursday "a trade deal with the US will be far better for them if they solve the North Korean problem!"

However, the US can only threaten North Korea with force or cut off business ties. North Korea's main backer for years has been China, which carries out 85% of North Korea's external trade and provides a similar percentage of its energy imports.

China could potentially curb North Korea's nuclear program through a limited deployment of military forces or by halting trade with the Hermit Kingdom. But China has a strong interest in preserving the North Korean state, as it acts as a buffer between the US's 25,000 permanently stationed troops in South Korea.

A Chinese envoy of diplomats arrived in South Korea on Monday and reportedly reached an agreement on how to handle North Korea's nuclear ambitions. It remains to be seen if the South Korean-Chinese action will be good enough for the Trump administration.