NO nation sold more weaponry to the developing world last year than the United States. According to the Congressional Research Service, the figure was $18.5 billion worth of fighting gear, with $14.5 billion of that amount going to the Middle East.The numbers aren't too surprising, given the unchallenged standing of the US as the world's premier military power and the surge in arms spending by Saudi Arabia following the Iraqi invasion of Kuwait. But they are disturbing to many Americans who like to think of their country as a force for peace rather than a supplier of guns. Despite that booming arms business, the US has ample opportunity to prove its peacemaking mettle. Washington has to sustain its efforts to revive the Middle East peace process. Just as important, it has to push vigorously ahead with that other indispensable ingredient for regional stability: arms control. As the leading arms merchant, the US is best positioned to curb the market. A good start was made last month in Paris, when the five largest arms suppliers - which also happen to be the five permanent members of the United Nations Security Council - met to discuss ways of controlling the flow of weaponry into the Middle East. The central business of the meeting dealt with the conventional arms flooding the region - though headlines emphasized the joint pledge to rid the Middle East of weapons of mass destruction. Representatives of the US, France, Britain, the Soviet Union, and China agreed to list the categories of weapons and technology that should be controlled. They committed themselves to working out criteria for permissible arms transfers. And they agreed to set up a consultative process for raising objections to arms sales. Technical experts from the five will meet in September to pursue this agenda, and another full plenary session is scheduled for October. The obstacles facing this undertaking are daunting. As a structure for limiting arms transfers to the Middle East takes shape, arms producers in the US and elsewhere are likely to raise the alarm. The countries that buy the weapons are going to have to recognize that their security is better served by limiting the fire power in their neighborhood, rather than continually adding to it. Smaller arms suppliers must be brought into the process. Much will depend on the depth of commitment in the White House. The Bush administration has tended to advocate both arms control and continued large arms transfers to the Middle East. The accent must be on the former.