Op-Ed: Tillerson is threatening North Korea, but here's his real target

Why is Secretary of State Rex Tillerson making saber rattling comments about how military action would be "on the table" if North Korea further provokes the U.S.?

Do he and President Donald Trump really want war with North Korea?

No. What they really want is to convince the rest of the world that we will consider some kind of military response. And they want the world to fear that possibility so much that they'll accept another kind of response instead. And of course that other response is tighter and more universally observed economic sanctions. In other words: If you really don't want war, then support some tougher penalties against Pyongyang.

There are two reasons why even strict sanctions on rogue nations don't lead to major policy changes or topple regimes. First, the dictators themselves like North Korea's Kim Jong Un and his inner circle do not personally suffer as whatever dwindling resources and luxuries the country can still obtain are hoarded by them.

Second, there are always some major countries that end up cheating the sanctions regime openly or clandestinely and thus give the sanctioned regime a lifeline. That's where that aforementioned "support" really comes in as the U.S. will need other nations to not only vote for new sanctions, but agree not to cheat the system too.

"To be blunt, China uses North Korea like a thug nation to do some of its dirtier jobs and act as a buffer against nations it sees as potentially hostile like South Korea and Japan."

Sadly, the "carrot and stick" approach doesn't work on both ends when it comes to rogue regimes like North Korea. The relaxation of sanctions against North Korea pushed by President Bill Clinton in the mid-1990s led to that nation getting billions of dollars in aid in return for halting its nuclear weapons program. But North Korea and the regime of Kim Jong Il cheated, and they went ahead with their nuclear project anyway.

Tillerson's threats of war are likely a calculated stab at getting more countries, especially Russia and the European Union nations, to get tougher for real. But one country is clearly the primary focus for Tillerson and the Trump administration: China.

It's China that will surely stand in the way of more sanctions and it's China that's going to have to ask itself just how far it's willing to go to keep protecting its communist neighbor and ally.

To be blunt, China uses North Korea like a thug nation to do some of its dirtier jobs and act as a buffer against nations it sees as potentially hostile like South Korea and Japan.

It also wants North Korea's regime to remain in place to avoid a massive refugee influx over its own borders. Maintaining that regime to serve those two goals is the reason China always opposes the toughest sanctions on Pyongyang and remains North Korea's only meaningful trading partner.

And therein lies the second major goal of Tillerson's tougher talk. The Trump team can't possibly hope that China will support new sanctions. But if Beijing becomes more worried about military action on its own border or has to manage even more of North Korea's economic needs after tougher sanctions are imposed, then China is that much less able to promote more adventurism of its own in the South China Sea and elsewhere.

China's continued demand for more military and economic respect is undermined almost daily by Kim Jong Un's missile tests and provocative statements and the White House wants to make Beijing pay the price fully.

If there was any doubt that this was the point of Tillerson's message, President Trump removed it Friday morning with the following tweet:

So make no mistake about Tillerson's comments. They are publicly directed at North Korea, but the primary target audience is China and the secondary audience is any other country that may want to stand in the way of sanctions. The U.S. is just as reluctant as always to actually fire a shot. The only question now is: Are any of the nations that Tillerson is targeting with his rhetoric willing to call that bluff?

Commentary by Jake Novak, CNBC.com senior columnist. Follow him on Twitter @jakejakeny.

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