Secretary of Defense Jim Mattis recently labeled North Korea the number one threat to the US, above Russia and terrorism, but the US can keep Kim Jong Un's burgeoning nuclear arsenal in check.
North Korea's vicious acts against civilians like Otto Warmbier, however, are much more difficult to rein in.
North Korea has a nuclear deterrent as well as a massive artillery installation that holds Seoul's metro area of about 25 million residents at risk, as well as 28,000 US military personnel permanently stationed in South Korea.
There's a huge risk that a conventional, non-nuclear confrontation with North Korea could quickly go nuclear, and for that reason the US would be reluctant to engage with the Kim regime militarily.
But North Korea has shown time and time again it's willing to detain, kidnap, torture, and kill outsiders.
One of these days, North Korea could go too far, provoke the US in a way that it felt it needs to respond, and a confrontation could start small before eventually going nuclear. And that's much more likely than an out-of-the-blue nuclear attack.
The list of incidents involving North Koreans and outsiders is long and gruesome, and unfortunately grew with the medical evacuation of Warmbier, who will likely never recover from the serious neurological injury he sustained under North Korea's care.
The US can sanction North Korea, cut it off from the international community, aggravate it with large-scale military drills and aircraft carriers just off its borders, but don't expect the US to attack North Korea — it's just too risky.
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