This link goes to the book "A War of Logistics: Parachutes and Porters in Indochina, 1945-1954".
https://books.google.com/books?id=IN...945%22&f=false
On page 164 (toward the bottom and following) is a discussion of material being flown in from the Philippines by American pilots. While the page initially seems to be blocked, scroll up and down and few times and the page appears (at least for me). The source was author Bernard Fall (who wrote "Street Without Joy"). He maintained that American pilots were flying arms and material into Viet Minh airfields near Vinh and Thanh Hoa in unmarked airplanes. The same pilots and planes were later found operating "privately chartered aircraft" for the Laotian government. The French intelligence services established a network of agents in the Philippines to report on the operations (departures of both ships and planes for Viet Nam). French forces in Viet Nam were then able to intercept and destroy many such ships and planes and the traffic was reduced after 1947.