'Brillig' was a British special forces operation to parachute a two-man Thai team of the Special Operations Executive’s Force 136 into the Nong Pla Dook area of Japanese-occupied Thailand to establish contact with the local resistance forces (6/7 September 1944).

The men were dropped from a Consolidated Liberator in the area of Hua Hin, and were met by a local team for transport by river to Samut Songkhram, where the boarded a train to reach Thonburi on 8 September. Here the men delivered a letter from Admiral the Lord Mountbatten, heading the South-East Asia Command, authorising them 'to find out how the Siamese resistance movement could work with the Allies, to promise to help, and to warn against premature action against the Japanese'.