THE REAGAN administration has maneuvered itself into an awkward corner in its fight against terrorism. Even as the president delivers an extraordinary speech accusing five "outlaw" governments of "acts of war" against the United States, the administration finds itself unable to put into effect the single, relatively modest step -- isolating Beirut airport -- it actually took after the recent hijacking. This painful contrast between word and deed comes at a moment when the president is struggling to convince would-be hijackers and alarmed American citizens, not to speak of his aroused political constituency, that he is dead serious about the issue.

President Reagan, in his speech before the American Bar Association, said that most of the terrorists attacking Americans are directly or indirectly controlled by a core group of radical, totalitarian governments. That much strikes us as unexceptionable, but unfortunately Mr. Reagan did not stop there. By citing Iran, Libya, North Korea, Cuba and Nicaragua as members of a "confederation of terrorist states," he provoked a distracting new debate on why he had lumped these five and excluded some others, and he spurred the distracting old debate on the nature of links among terrorists. By describing the deeds attributed to the five as "acts of war," he drew upon himself more of the pressure to respond forcibly, and more of the counterpressure not to respond irresponsibly, that has buffeted him throughout this crisis.

The Beirut flap is a special embarrassment. The Lebanon government, which was nowhere to be seen during the hijacking, has found its voice and is mobilizing its Arab friends to oppose the airport boycott the administration was trying to organize. America's own allies, meanwhile, avert their gaze. The administration is being forced to give way to the Lebanese government -- in its way a more cutting humiliation than the one extracted by the terrorists. That government's weakness had made Beirut a terrorist's playground; an airport boycott might have encouraged the nongovernmental powers-that-be in Lebanon to clamp down. For that to happen, however, the United States needed a lot more international cooperation than it was able to secure.

The administration has put itself into a trap of its own making in which its steps against terrorism are constantly being measured against, and overwhelmed by, the tremendous public priority it assigns to the battle. It has to strike a better balance between the militancy of its statements and the strength of the actions available to it.