Vang Pao, the Laotian general who marshalled a CIA mercenary army to fight a “secret war” against communist insurgents in the remote mountains of Laos in the 1960s, has died aged 81. Although Vang Pao’s supporters portrayed him as a father figure uniting all his people, the Hmong (an ethnic minority in Laos), on the side of the US against the communist world, his critics regarded him as a charismatic but ruthless opium warlord, who made arrogant and misleading claims to speak on behalf of all Hmong. Far from uniting the Hmong, they say, he divided them. Some historians argue that he allowed his “secret army” to be used as cannon-fodder, played as pawns on a CIA geopolitical chessboard.

Certainly his attempt to align all the Hmong clans with the US military and its war strategy divided his people, with the Hmong tribal minority clans fighting on both sides, for and against the communist-led Pathet Lao movement.

Vang Pao was born in Xieng Khouang province, in north-eastern Laos. His military career began in the French colonial army that fought the Japanese and then Lao nationalists. During the 1950s, Ho Chi Minh’s Vietminh guerrillas, and Lao and Cambodian nationalists united in a struggle to defeat the French empire in Indochina.

After the French defeat in 1954 and its withdrawal from Indochina, the US military gradually escalated its intervention in Vietnam. Meanwhile in neighbouring neutral Laos, Washington’s strategists opted for a secret war against North Vietnam, without ground troops. This opened the door for the CIA to take charge in the 1960s.

Major Vang Pao was plucked from the ranks of the Royal Lao Army and recruited to play a key role in this CIA campaign, in command of a mercenary army of Hmong forces supplemented by 10,000 Asians, including Thai regular soldiers, Chinese Kuomintang, Burmese and Filipinos. He ran the CIA’s secret army from 1962 to 1975.

This covert war was also waged with the assistance of B-52 aerial bombardments and regular supply flights from Air America, a commercial airline fronting for the CIA, which flew in food and ammunition to mountain helipads cut out of the jungle. It was a war that the US public was not allowed to see or know about.

Air America pilots have since admitted that their planes not only transported rice, bullets and weapons, but also sacks of opium grown by the Hmong villages. Smuggled narcotics became a routine cargo transported from Laos and delivered into the corrupt arms of a clique of South Vietnamese generals in Saigon. Vang Pao even set up a heroin laboratory at the secret US CIA base at Long Cheng. The trade helped to fund Vang Pao’s army, with the complicity of senior CIA operatives.

Dazzled by the whirl of US airpower bringing 24-hour food and military supplies to his men in the remote mountains near the Plain of Jars, Vang Pao came to believe in the Chao Fa legend of an independent Hmong state.

Reality soon dispersed that dreamworld. Vang Pao later admitted that his Hmong soldiers suffered appalling losses fighting around the Plain of Jars, in Xieng Khouang province. He put the figure at 17,000 dead by 1968. But his CIA controllers urged him to keep on fighting. US sources, including the historian Alfred McCoy, have noted that younger and younger fighters were forcibly enrolled. By 1968, 30% of the new recruits were only 14 years old.

The Pathet Lao leadership, hiding in caves, survived one of history’s most brutal aerial bombardments, and by 1975 had taken full control and established a communist government. The CIA arranged for flights to bring Vang Pao and his Hmong supporters to the US as refugees via airbases in Thailand. Thousands more beleaguered Vang Pao supporters fled across the Mekong and ended up in refugee camps.

In the US, Vang Pao assembled anti-communist exiles under one banner – the United Lao Liberation Front – and sent funds and weapons to be ferried across the border from Thailand to the bands of hardcore Hmong determined to resist the new regime. Many of them fought on in the belief that their beloved general would one day return from the US to “liberate the country”.

Vang Pao has been widely portrayed by his Hmong supporters and the US media as an American war hero and venerated leader of the Hmong people. The former CIA chief William Colby once called him “the biggest hero of the Vietnam war”. He came very close to having a park in Madison City, Wisconsin, named after him in 2002. But McCoy objected to the honouring of a man who had ordered the summary executions of prisoners and soldiers who crossed him, and accused Vang Pao of war crimes and heroin-trafficking. Five years later, Vang Pao’s name was removed from a new school in Madison after opponents said it should not bear the name of a man with such a blood-stained history.

His reputation was further damaged when he was arrested in 2007, with other Hmong activists and a retired US military officer, for conspiracy to procure weapons of war, including Stinger missiles, to launch a terrorist attack on strategic buildings in Vientiane, the Laotian capital. In 2009, charges were quietly dropped against Vang Pao.

He was married to five women but was forced to divorce four of them when he arrived in the US. He is survived by his son, Chu Vang. It has been reported Vang Pao fathered more than 20 children.

Tom Fawthrop

• Vang Pao, soldier, born 8 December 1929; died 6 January 2011.