THERE HAS been much hopeful celebration of the agreement reached by the Permanent Five members of the Security Council on Cambodia. There deserves to be even more now that the four Cambodian parties have signed on. The Hanoi-seated Hun Sen government plus the two non-Communist resistance factions and the powerful China-backed Khmer Rouge handily passed their first test of setting up a council to hold formal Cambodian sovereignty while the United Nations takes over much of the national administration and runs elections. A promise of rescuing Cambodia from deepening civil war and further Khmer Rouge genocide gleams.

Except that the process is unfolding in disturbing neglect of the question of who is to pay the bills. To take the first diplomatic step envisioned by the "Perm Five" -- shifting Cambodia's General Assembly seat from the resistance coalition dominated by the Khmer Rouge to the new Supreme National Council -- is not a big cost item. But to put the requisite thousands of military peacekeepers and thousand or more civilian administrators on the ground could take $2 billion. Is there not a cheaper model? No doubt there is, but then the question becomes whether it will work. The reason the "Perm Five" agreed to take over a warring country to deliver it to peace was not through a softness for international experiment but because they figured nothing less audacious would do. Without assurance that the bills can be paid, it becomes fraudulent to imagine that Cambodia can escape its terrible plight.

The United Nations is everybody's choice to do the heavy international lifting. But the place is broke. The United States is in arrears by two-thirds of a billion dollars. The House has accepted the Bush administration's proposal for a five-year repay schedule, but the Senate has not even acted on it. The costs of saving Cambodia would come in on top of that. Nor is Cambodia the only cause endangered by the disconnect between the transfixing vision of a vibrant diplomacy and the myopia of national budgeting. Today, for instance, Haiti will be asking the U.N. to monitor and render secure its next elections -- a $10 million item that the U.N. should be able to pay out of petty cash. Diplomacy is only part of the stuff international dreams are made of. Money is a part too.