The United States has recently declared that its policy toward Cambodia is on the right track and doesn't need to be changed, but it seems to me that its policy is changing and this is the best thing about it.

The old policy was to support the inclusion of the Khmer Rouge in a power-sharing arrangement meant to arrange elections. (The Khmer Rouge is the Communist faction that committed genocide upon its countrymen in the 1970s, was then driven out by an invading Vietnam, and has since been struggling to return to power.) That policy had a certain rationale: to bring the Khmer Rouge in to contain them rather than leaving them outside uncontained. But it was an unconvincing rationale that disgusted many people and left them suspecting that the Bush administration harbored ulterior motives -- to play up to the Khmer Rouge's patrons in China, for instance, or to be faithful to a particular conservative memory of the Vietnam war.

The new policy is to enlist the Chinese, the Soviets, patrons of the Hanoi-supported Hun Sen regime in Phnom Penh, plus the British and French, in creating an unprecedented United Nations-sponsored entity that would assume working sovereignty over Cambodia and move on from there to hold elections.

That the American government does not say much to acknowledge what I take to be a major policy reversal can be attributed to several considerations. First, the Bush administration may be embarrassed -- and with reason -- to say that it has changed course. Second, the U.N. idea is provisional, airy and awash in uncertainty. Third, the situation on the ground is unusually fluid and murky.

The upshot of all this is that American policy is poorly understood, or at the least poorly communicated, by many diplomats and others. It is possible to be in a room of specialists and to find no one who is quite sure of what the policy is. Nor has it been a golden hour for journalists. For instance, last month's widely noted ABC News program on Cambodia, which for all its flaws correctly underlined the unconscionable indirect comfort that American policy has afforded the detested Khmer Rouge, missed the crucial point that the policy was changing.

The principal author of the new policy is Rep. Stephen Solarz (D-N.Y.). What he did was to break through the wearying stalemate in American thinking about Cambodia -- the argument between policy advocates who rejected Hun Sen on grounds that he is a client of Vietnam and a former Khmer Rouge with his own crimes to account for and policy critics who favor supporting Hun Sen as a Cambodian Gorbachev or, at the least, as a shield against the Khmer Rouge. The breakthrough consisted of moving beyond an either-or choice among directly competing Cambodians into a broader framework in which outside forces would try to control and muffle the competition.

Having made himself over the last decade the world's key figure in Cambodia diplomacy -- the one person who paid attention and had all the connections -- Solarz was in a position to hatch a promising idea. He was also in a position to promote it to an able and ready government, Australia, which made it the basis of the current striving for a U.N. solution.

Indochina expert Stephen Young finds a ''genius'' in the Solarz idea: it diffuses the Cambodian political confrontation by parking sovereignty temporarily in a kind of ''trust'' under the U.N. Security Council, whose five permanent members are here in rare common flight. It matters greatly, too, that there are some favorable aspects to the timing: the Soviet Union is in a de'tente mode, specialists see interesting hints of a partial Chinese-Vietnamese thawing, the United States needed a better idea, Southeast Asia aches for respite.

U.N. Secretary General Javier Perez de Cuellar offers some well-informed cautions. Before the U.N. takes on such an immense new burden, he says, the ''Perm Five'' must define a specific U.N. mandate, bring the Khmer Rouge into a cease-fire so that peace-keepers won't have a security problem, and put up the funds -- we're talking up to $5 billion for 10,000 or 20,000 men.

This week, the Perm Five handed off part of their diplomatic mission to Japan, which has 1) deep pockets and 2) a desire to spread its diplomatic wings. New at international conflict management, the Japanese tripped a bit, but the process stumbles on. It is the only game going, and a desperate long shot, and it would be an unconscionable betrayal of Cambodia not to try to pull it off.