China’s new aircraft carrier battle group has entered the South China Sea, destination unknown.  The Liaoying and her five escorting warships cleared the 90-mile strait between Taiwan and the Philippines on Monday night.

Is the battle group "on routine patrol"?

On a training mission?

Showing the flag?

Or is it going to screen a ChiCom deployment of troops, warplanes, missiles, and equipment to the three new, fortified, man-made islands China has built in international waters of the South China Sea?  Defense thinker Robert D. Kaplan labeled the South China Sea “Asia’s cauldron” in his 2014 book of that title.

That strategic body of water seems destined to be the testing ground for whether China wishes to be part of the existing world order.

On the evidence so far, there’s considerable room for doubt.  China’s actions in the South China Sea are Exhibit “A.”  The Permanent Court of Arbitration ruled in July that China's building of man-made islands on uninhabitable shoals and rocks in the South China Sea violates international law.

So far, Beijing has ignored the ruling and kept right on building.

The Georgetown University Center for Strategic and International Studies broke the news just before Christmas that three of the man-made islands China has constructed now have defensive fortifications, airstrips, and barracks.  One has a deep harbor the size of Pearl Harbor (where President Obama and Japanese P.M. Shinzō Abe are meeting today).

Is the Liaoyang headed there?

China has now plainly broken out of the so-called nine-dash line – and also penetrated the U.S.'s 56-year-old defense perimeter in East Asia.

The short-term question posed by the carrier group’s deployment is whether, as Russia has done in Syria, the Chinese are trying to "run the board" before Mr. Trump takes office on January 20.  We’ll know soon enough.

Here’s the long-term challenge.

If China mans those three fortified islands in the South China Sea (and especially if it also declares the area an Air Defense Identification Zone, as it did in the East China Sea at the beginning of this year), China will have overturned the balance of power, which has existed in East Asia since the end of WWII.  It will also present the incoming Trump administration with its first major foreign policy crisis.

Meanwhile, at the other end of what geographer Halford Makinder called "the World Island," the Russians have taken effective control of the eastern Mediterranean.  And the Russian carrier strike group remains deployed off Syria.

Now for the 64,000-Dollar Question.

Where are the American carriers?  Where are the capital ships of the United States Navy?

Nowhere to be seen.

According to gonavy.jp, the U.S. Navy's nine supercarrier strike groups are all in their home ports, except for one, which is returning to Norfolk from the Persian Gulf.  It's in the mid-Atlantic.

In other words, the Obama administration has withdrawn the U.S. Navy from the oceans of the world.  No one is policing the global commons.  The American cop has walked off the beat.

China admitted last December that it is building a second aircraft carrier.  It’s believed to be beginning construction of a third.  An editorial in the Global Times, China's government-controlled leading English-language newspaper, predicted that China will soon have naval basing rights in South America.  It said: "The Chinese fleet will cruise to the Eastern Pacific sooner or later.  When China's aircraft carrier fleet appears in offshore areas of the U.S. one day, it will trigger intense thinking about maritime rules."

Interesting times.  But at least Mr. Obama – who, by pulling the U.S. Navy back to the mainland, ended the forward deployment that began after WWII – will be gone.  He and Secretary of State Kerry have successfully gone a significant distance toward taking the United States down as the sole global superpower.

That was their goal, and they have done it.

And now?  Who knows?  Maybe the next American president will again be willing to be the Leader of the Free World.

The whole world will be watching for the answer to that question.