What is the World War 2 history of the airfield located in Udorn Thailand?

I thought Udorn was built by the United States military in the 1960's to be used during the Vietnam War. There is not much in writing about Thailand's assistance of the Japanese in WW2, and Thailand's brief skirmishes with the Vichy French in Indochina in the 1940's.

The original shorrt airfield, (the one used by Air America during war in Laos and Vietnam) I believe was built by the Japanese during WWII. They built many airfields in SEA, especially in Thailand and Laos.

In the late 50's, the US, under Eisenhower, built a 10,000 foot runway there, in case bomber strikes against China were called for. I believe this airstrip lay dormant until about 1963-64 when the first Air Force troops began filtering in.

I remember rummaging through an old hanger which was a bit removed from the flightline there, maybe 300 yards away, in 1966. and finding several signs with Japanese writing on them. Wish I had kept one. I wonder if anyone has any history of the original field which was built by the Japanese during WWII? Any information appreciated. Maybe some Air America types know a little bit more about the original strip. I was there 1966-67, working on Electronic Countermeasures.