US prosecutors have charged nine people with plotting a coup in Laos, in a conspiracy to murder thousands.
Gen Pao emigrated to the US from Laos in the 1970s
The suspects were seized in dawn raids across California following a six-month covert investigation by US police.
Officials say the detained ringleaders include Gen Vang Pao, a prominent member of the ethnic Hmong group who emigrated to the US in the 1970s.
As a Laotian general, he led CIA-backed forces that fought communist guerrillas before they seized power in 1975.
HMONG IN LAOS
Ethnic group that often complains of marginalisation in Lao society
Took the side of the US in the Vietnam War - and say they are persecuted because of it
Many still live in jungles
Small numbers say they are fighting a rebel insurgency
Thousands have fled to Thailand in recent years
US took in 14,000 Hmong recently, but has no plans for taking more
The accused allegedly conspired to buy hundreds of machine-guns, rockets and explosives from US federal agents who were working undercover as arms dealers.
They are said to have sought to spend millions of dollars on weapons to carry out attacks.
Prosecutors said the coup leaders planned to blow up government buildings and kill "thousands of people".
The "Hmong insurgency planned to use AK-47 automatic rifles, Stinger missiles, LAW rockets, anti-tank rockets and other arms and munitions to topple [the] Lao government and reduce government buildings in Vientiane to rubble," a public prosecutor in California said in a statement.
Laos Foreign Ministry spokesman Yong Chanhthalansy said it was "great news" for Laos.
"We hope the United States will prosecute them strictly under the Patriot Act and punish the violators of the law severely," he told the Reuters news agency.
Mr Yong said he hoped the development would improve relations with neighbouring Thailand, whom Vientiane has suspected of turning a blind eye to Hmong militant activity within its borders.
"I am sure that such vigorous investigation will lead to the uprooting of the network of the villains who have caused the most difficulty in bilateral relations between the Lao and Thai governments," he said.
The defendants could face life in prison if found guilty.
A 10th person was arrested but has not been charged.