Non-aggression Pacts with the British and the French

Non-aggression Pacts the British and the French



The Non-Aggression Pacts were signed on June 12, 1940 with Great Britain and France, and a Treaty of Friendship was signed on the same day with Japan, the Phibunsonggram Government maintained the balance between Britain and Japan but clearly showed its determination to take advantage of France’s weak position to regain lost territories in Indo-China.




In negotiating the Non-Aggression pact with the French, the Phibunsonggram Government took advantage of the friendly attitude of Britain to secure a concession from France. It profited from the tactic of playing off one enemy against the other.



The success of this tactic was enhanced by Japan’s southwards advance from China and the rise of Thai nationalism, irredentism and “Pan-Thai-ism” at home. These internal and external factors challenged the political positions of both Britain and France in Asia, and the two powers were obliged to come to terms with Thailand.



As far as negotiations over the non-aggression pacts with the British and the French were concerned, the Thais took advantage of the friendly attitude of the former to secure a concession from the French. The French concession was the agreement to readjust the boundaries along the Mekong River. With respect to this agreement, confidential and secret letters were exchanged when the Franco-Thai non-aggression pact was signed on June 12, 1940.



The contents of these letters are significant in that they confirmed that France had agreed to move the Thai-Lao boundary on the Mekong River to the line of the thalweg and recognize any territory on the western side of the thalweg as Thai. The Thai government hoped to eliminate the original manner of delimitation of the boundary line in the Mekong River.



In principle, the whole Mekong belonged to France. The thalweg had been adopted as a boundary only in stretches where there were no islands. Where there were islands, they belonged to France with the exception of certain islets which were definitely connected to the Thai shore. This system of delimination was dictated by France in the treaty of October 3, 1893. On February 14, 1925, another treaty had been signed with France, whereby the latter agreed to accept the thalweg as the Mekong River borderline except where there were islands in the river, in which case the river-line border would be the channel between the islands and the Thai bank.



The confidential and secret letters of June 12, 1940 stated that these new arrangements were to be determined by a new mixed commission of representatives from both countries, and that the border negotiations would take place before ratification of the pact.



As these secret letters also stated that the French negotiating team would be led by an official of ambassadorial rank from Paris who would be empowered to negotiate “other problems” (apart from the thalweg of the Mekong River), many authorities on Thai politics, including Flood, believed that the phrase “other problems” was related to the question of the return of those enclaves across from Luang Prabang and Pakse which the Thais had ceded to French in 1904.




However, evidence available in the official files of the Thai government indicated that the phrase “other problems” referred only to the problems of the river patrol police, fishing and navigation in the Mekong River, as well as a lease of forestry and the problem of the French subjects residing in Thailand.



It was not yet related to the question of the return of the enclaves across from Luang Prabang and Pakse in Laos. The latter issue was raised by the Thai government only after the French military collapse in Europe on June 14, 1940.



This event made its possible for Thailand to be more aggressive in pursuit of its territorial objective in Indo-China.