Former Cambodian leader Prince Norodom Sihanouk is visiting Washington to enlist support for an army to fight the Vietnamese occupying his country and promote himself as the future leader of a neutral, independent Cambodia.

A high-ranking State Department official stressed, however, that Secretary of State Cyrus Vance decided to host Sihanouk as a private guest of the government in order to "show respect for him as a historical figure," not to grant approval for Sihanouk's projected army. Sihanouk, Cambodia's former king and elected head of state, was deposed by Lon Nol in 1970.

The prince is being treated as a man with a future as well. Vance, Assistant Secretary of State Richard Holbrooke and Ambassador for Refugee Affairs Victor Palmieri will confer with Sihanouk. Morton Abramowitz, U.S. ambassador to Thailand, arrived in Washington yesterday for consultations and a meeting with Sihanouk Saturday.

After his final conversation with Holbrooke, Sihanouk said he was advised to improve his relations with the Association of Southeast Asian Nations, especially Thailand, and with China and to work for unification of the various Cambodian refugee factions. Sihanouk will be in the United States until mid-March.

Sihanouk said Holbrooke told him that he should ask for the help of Singapore strongman Lee Kuan Yew in obtaining the permission of Bangkok authorities to visit the thousands of Cambodian refugees in Thailand. "Your government tells me to go to Singapore, not [to] the White House or the State Department," Sihanouk chuckled.

Dispite his plans for mounting an insurgency, the prince came to Washington without a "Sihanouk solution." He said he has abandoned the quest for a peaceful resolution of the Cambodian conflict, arguing that an international conference would be impractical now since neither Vietnam, the Soviet Union nor China would attend.

"It is a nightmare," Sihanouk told members of Congress and journalists. "China wants to fight by proxy to the end . . . The Vietnamese, they are like a man who has a very delicious piece of cake in his mouth -- Cambodia -- and all that man can do is swallow the cake."

In such a contest, Sihanouk said, his only chance for having a voice in Cambodia's future is to field an army. "We cannot defeat the invincible Vietnamese Army, we can only weaken them. Then they may withdraw," he said.

But Sihanouk's choice of military commanders -- Cambodian Gen. Sosthene Fernandez -- had led some Cambodian figures and American officials to question the wisdom of the prince's proposal. Fernandez commanded Lon Nol's forces against the Khmer Rouge and Shihanouk during the 1970-75 war and had a reputation for being corrupt. He was also one of the men held most responsible for the 1970 pogrom of Vietnamese in Cambodia.

"Yes, there was corruption but they have learned corruption does not work. I have Sosthene Fernandez and a small team of former Lon Nol officers because the United States gives aid to Lon Nol," Sihanouk said.

Sihanouk said he has not asked the United States directly for military aid. "I do not want to embarrass your government," he said. "I respect the sovereignty of the United States."

Instead, Sihanouk is fostering the idea here, in Canada and in Europe that he will be the popular choice to lead Cambodia should the 200,000 Vietnamese soldiers ever withdraw.

Ironically, while the prince chastizes the communist world for tearing his country apart in the hope that the "free world" will intervene in saving Cambodia, the round-the-world airfare for Sihanouk and his wife, Princess Moniquie, is paid for by Kim II Sung, head of communist North Korea.

"This could well be the first joint venture of the United States and North Korea," said an American official. "The man is amazing."