Ky, 73, of Hacienda Heights, California, arrived in Ho Chi Minh City's Tan Son Nhat Airport with his wife, daughter and three friends, becoming one of the best-known political figures from the former U.S.-backed South Vietnamese government to return.
"A lot of people said 'Don't go, don't go,' but I said this is my home, my country," Ky said as he was driven in a van from the airport. "We Asians, we believe in destiny, so it's the right time, the right moment to come."
Arriving at his hotel, Ky reached out to give a warm hug to his former bodyguard who had come to greet him, along with a small crowd of friends, some bearing flowers.
Vietnam, which issued a tourist visa to Ky, has said it welcomes his decision "to come back to the homeland ... after many years apart."
Prior to his return, which coincides with Tet Lunar New Year festivities, Ky, a long-standing critic of the Communist leadership in Hanoi, said in interviews that he wants to bring a message of reconciliation on his trip.
"The war ended 30 years ago, but it still divides us into two camps. So I want to put aside the past hatred, and just sit together and talk to one another, face to face," he told Radio Free Asia. "And I believe if everybody loves the country and loves its people, we will sit together as one."
He is expected to visit friends and family in Ho Chi Minh City before flying to Hanoi Jan. 28 and visiting his hometown of Son Tay, about 25 miles northwest of the capital.
Ky, one of the most colorful leaders during the Vietnam War, was a flamboyant fighter pilot who became premier following a military coup in 1965. U.S. officials were wary of his reputation as a playboy with a fondness for drinking, gambling and womanizing.
The one-time air force general went on to serve as vice president under Nguyen Van Thieu in 1967-1971.
In 1975, when Communist North Vietnamese forces took over Saigon, the capital of U.S-backed South Vietnam, Ky escaped by flying a helicopter out to sea, landing on a U.S. naval carrier. A resident of southern California since then, he became a businessman. He also wrote several books and lectured at universities.
In southern California - which has the largest Vietnamese population in the U.S. - some activists have condemned Ky's visit to Vietnam, arguing it bestows legitimacy on a corrupt government.
But Ky's visit underscores a significant shift in attitudes among many overseas Vietnamese - the "Viet kieu" - hundreds of thousands of whom fled the Communist regime decades ago. Increasingly, through travel and business deals, they are renewing ties with their homeland.
In recent years, hundreds of thousands of Viet kieu have returned for visits, with an estimated 200,000 flooding home annually for Tet celebrations, which begin Jan. 22 this year. More than US$2 billion in remittances was sent to Vietnam in 2002.
There are an estimated 2.7 million Viet kieu, including about 1.3 million in the United States.
Communist Vietnam, which once viewed the returnees with outright suspicion and hostility, has changed its approach, now actively wooing overseas Vietnamese to return as tourists or to invest and do business in their homeland.
In Ho Chi Minh City on Wednesday, the welcome for Ky was echoed by Doan Dinh Nhat, 65, a former soldier in the South Vietnamese army who spent three years in re-education camp after the war.
"He's been away a long time so it's a good chance for him to come back. It's normal that he wants to come home. If we stay bitter, it doesn't change anything," said Nhat, a motorbike taxi driver.
By Tini Tran