Country between Thailand and Vietnam (4)

I believe the answer is:

laos

(Other definitions for laos that I've seen before include "Mountainous state in southeastern Asia" , "Landlocked south-east Asian country" , "Asian country, capital Vientiane" , "SE Asian country" , "Landlocked state in southeastern Asia" .)

I've seen this clue in The New York Times and the LA Times.

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