Becoming interested in nationalist politics in his early teens, the fourteen-year-old Thuỷ entered the Revolutionary Youth League of the communist leader Ho Chi Minh.

The Assembly was started by the Viet Minh as a vehicle of resistance against French colonial rule in what would become the First Indochina War.

Speaking both French and Chinese fluently and known as an expert in agitprop, Thuỷ traveled both Asia and Europe visiting Vienna, Stockholm, Rangoon, Beijing, and Moscow in 1950 to gather support for the Vietnamese cause.

Thuỷ's health was cited as the reason for his resignation, yet his losing a power struggle, in which he supported a pro-Soviet line, is the more likely cause.

Thuỷ then fell out of favor with the ruling party, but he returned to the political scene in 1968, as the DRV’s chief diplomat at the Paris peace talks.