The situation in the South China Sea continued to escalate this month, with China charging that a December 10 flight by one of two U.S. B-52 bombers flew within two miles of one of its "islands" in the the contest territory. The Pentagon claimed it was looking into the incident and has stated if true, the violation of Chinese territorial sovereignty was unintentional.

China described the incident as a "serious military provocation" and warned such actions "must be prevented."

Over the past 18 months, China has used dredgers to enlarge several reefs in the South China Sea. Under international law, terrain features that disappear at high tide do not count as sovereign territory, with a 12 mile territorial boundary and 200 mile economic exclusion zone. China has used these artificial islands-and the boundaries they project-to support its claim to approximately 90 percent of the South China Sea.

Other countries in the region, and the United States and Australia, have been pushing back against these claims. The U.S. Navy and Air Force have run several "Freedom of Navigation" exercises, sailing and flying right up to the boundaries of China's claimed airspace, as allowed under international law.

Last week, a Royal Australian Air Force P-3C Orion maritime patrol plane flew a similar mission in the South China Sea. In response, the Chinese state newspaper Global Times stated, "Australian military planes better not regularly come to the South China Sea to 'get involved'…it would be a shame if one day a plane fell from the sky and it happened to be Australian."

The Pentagon claims the flight was a "routine training mission" and not a Freedom of Navigation exercise, and that bad weather might have been to blame for the bomber veering off course.

A B-52 will cover 9.4 miles a minute at cruise speed, meaning it would take being off course for just one minute to make such a mistake. That's not a lot of time.

On the other hand, a lot of factors should have prevented such an error. B-52 bombers have a dedicated navigator crew member, and GPS is generally unaffected by bad weather. Further, any flight near claimed Chinese territory in the South China Sea would almost certainly be painstakingly plotted and navigated in order to avoid just this kind of international incident.

The U.S. had previously told China that there would be no more Freedom of Navigation voyages by U.S. Navy ships until 2016. In hindsight, the statement makes a curious omission: it makes no mention of flights by aircraft.