The Vietnam War raged for decades. Fearing the spread of communism, the United States initially joined the conflict in secret, later openly and with increasing ferocity in the fight against North Vietnam and its Chinese and Soviet sponsors. After US public opinion turned against the war in response to heavy losses and reports of frontline brutality, peace talks began in Paris in 1968. A breakthrough was achieved in separate, secret talks between US National Security Adviser Henry Kissinger and Lê Duc Tho, a member of North Vietnam's politburo. This resulted in the 1973 Paris Peace Accords and the withdrawal of US forces.