ETHIOPIA'S new foreign minister, Seyoum Mesfin, was in Washington recently, explaining to administration officials, lawmakers, and others what the new government in Addis Ababa has done and seeking American support for its reconstruction effort.He came to the United States with a persuasive brief. Minister Seyoum's report gives the measure of the vast changes that have taken place in Ethiopia since the Mengistu dictatorship fell last May. The dreaded security police has been disbanded; the torture chambers closed down; the hated system of military conscription ended and dissolved. The civil war is over, freedom of speech and the press have been restored, and the government has committed itself to multiparty democracy, administrative decentraliz ation, and a free market economy. It was not only what Seyoum said but how he said it that impressed. Here for the first time in as long as anyone could remember was a senior Ethiopian official who spoke straightforwardly, who answered tough questions candidly rather than trying to dance around them. And who, when he spoke of democracy and respect for human rights, did so with seemingly genuine fervor. Of course not all can be accomplished in a few months. President Meles Zenawi and his associates still have to prove that they mean what they say about democracy and respect for human rights. But for some things a stroke of the pen has sufficed. By discarding the previous regime's agricultural marketing system that obliged farmers to sell to the state at giveaway prices, the new government has taken a big step toward boosting food production. With good rains, Ethiopia could get off the international dole in two or three years. Until then, however, it will still need help from abroad. The government estimates that 300,000 tons of foreign food aid will be required during the first six months of 1992 to stave off famine. The US will continue to be in the front ranks of donors of humanitarian food aid, as it was in the past when Ethiopia was run by a Marxist-Leninist dictatorship defiantly hostile to the West. Regrettably, however, it may not soon be prominent among those Western aid donor states helping the new government of Ethiopia rebuild the country from the ravages of decades of civil war. It seems truly absurd that four months after Mengistu's fall, legislation enacted in 1988 to prohibit aid to his regime should still bar the US from helping a successor who has repudiated all the practices that prompted the ban. And even when this legislative barrier is removed, there will remain the complicated matter of an Ethiopian government debt, dating from the 1970s, that triggers a congressional aid ban. At the State Department and in Congress, procedures have been put in motion to overcome these two obstacles. Unfortunately, they seem to lack the kind of high-level executive and legislative branch push needed to propel them quickly through the bureaucracy and through Congress. No one, least of all the new government in Addis Ababa, expects the US to take on the job of rebuilding Ethiopia's economy. That is a task for Ethiopians. Foreign aid will be a component of it, but even there the main burden is likely to be borne by the Europeans. What is important is that the US show its support for President Meles's reforms and for Ethiopia's aspirations for democracy by joining the ranks of development-aid donors. Through its active and skillful diplomacy over the past two years, Washington has contributed immensely to restoring hope for progress, stability, and democracy in Ethiopia. It should not hold back now.