In reference to the column "An Indefensible Cambodia Policy" by Mary McGrory {June 21}, I am certain that Karl D. Jackson of the National Security Council, who wrote the book "Cambodia 1975-1978, Rendezvous With Death," fully understands Cambodian history and the Cambodian problem, as do President Bush, his administration, Sen. Charles Robb (D-Va.) and Rep. Stephen Solarz (D-N.Y.).

Cambodia is not Nicaragua. Nicaragua is controlled only by the Nicaraguan people. Cambodia is now dominated by Vietnam, and about a million Vietnamese colonists are settling there. China and the Soviet Union are behind the Cambodian war. To end that war and suffering, I think there is a need for a policy that stops China, the Soviet Union, Vietnam and other countries from supplying arms and ammunition to the warring factions.

Also Vietnam has to accept U.N. verification of its withdrawals. To defeat 35,000 well-armed Khmer Rouge, the United States should help the Cambodian people elect a government of their choice. No one outside Cambodia can possibly understand the hatred and fear we Cambodians have for the Khmer Rouge. The Cambodian people will express their disapproval at the ballot box.

Recently President Bush reaffirmed the U.S. policy toward Cambodia; the United States should commit to a comprehensive political settlement plan under which the U.N. plays a strong role in solving the Cambodian conflict. Such a plan, which calls for a U.N. administration with a Cambodian Supreme National Council representing Cambodian sovereignty, is not an alternative plan to the original Australian initiative, as Mary McGrory has mentioned. It is the same plan. This is the only way to help the Cambodian people achieve their right to self-determination. The United States should lead China toward this policy. Any delay only benefits the Khmer Rouge or Vietnam. VANN M. YANN Annandale The writer is co-leader of the Cambodian Network Council, an educational nonprofit group.