China’s mysterious initial refusal to let the USS Kitty Hawk and its five escort ships dock in Hong Kong for a four-day Thanksgiving layover is still the source of speculation.

China hasn’t explained why it denied the docking rights as the ships sailed toward Hong Kong , nor has it said why it reversed course once the ships had already veered toward their homeport in Japan. The sailors had to eat Thanksgiving dinner aboard their vessels. Read news stories here and here.

Both sides are left a bit raw over the incident.

Here are the two plausible explanations I’m hearing.

1) China is still angry over the October reception given to the Dalai Lama in Washington, in which President Bush received the Tibetan spiritual leader in the White House and Congress granted him its highest award.

2) The port call coincided with a large-scale naval and air operation by the People’s Liberation Army along coastal China, and would have put the U.S. ships in easy monitoring distance of the exercises.

The Chinese military exercise has put a crimp on commercial aviation along much of eastern China’s seaboard, backing flights up. It is not unprecedented that military exercises would disrupt commercial aviation. Back on Dec. 1, 2006, the Shanghai Pudong International Airport was simply shut down for two hours with no explanation, forcing international flights to turn back or land elsewhere.

The incident is certainly a step backward after the announcement earlier this month that Beijing and Washington agreed to set up a telephone hotline between the two defense establishments to prevent any misunderstandings from flaring up.

Of course, there is a third possible explanation, and that is that some unknown incident by Washington was seen as provocative by Beijing, and this is the response. We may never know if that is the case.