BY HIS latest act of phony ''humanitarianism,'' Saddam Hussein should further worsen his reputation around the world. He did offer to free all foreign women and children but promptly imposed new bureaucratic obstacles (a requirement for exit visas) as well as political ones (a demand that planes sent in for detainees must arrive in Baghdad laden with embargo-busting supplies). In weighing his policy, it helps to remember that what he is now reversing is his own cruel tactic of taking all these people captive, for which he now expects plaudits. For him to pronounce himself ''deeply affected'' by the plight of his prisoners, and on that basis to release only some of them, is doubly disgusting. No less disturbing is his report that he is keeping Iraqi families (''including some pretty children, just as pretty as the {Western} children that we have here'') as hostages at ''prime targets.'' As he loosens his grip on some Western hostages, meanwhile, he tightens his grip on others. The men may be at greater risk for losing whatever protection might have been added by the company of women and children.

What might Saddam Hussein have in mind in playing the "humanitarian," other than distracting attention from his continued use of foreign (and Iraqi) bodies as shields against attack? Some of the people he holds happened to be merely changing planes; others have years of residence in and service to Iraq. Even as Iraq keeps thousands prisoner, moreover, it expels some American diplomats; conceivably it is kicking out some people it is refusing to let out. All this reflects a certain haste and inconsistency in President Hussein's policy. Plainly, he has been thrown off his stride by the many-leveled resistance that met his aggression in Kuwait. With the United Nations secretary general arriving in the region, perhaps he thought the moment was ripe to add a supposed humanitarian initiative to his appeals for a diplomatic solution.

There is much discussion these days of whether the American public has the stamina for a long, difficult and dangerous crisis. We don't know the answer to that one, but we feel we have a pretty good idea of what the public thinks of a foreign leader who attempts to divide and confuse Americans by playing on their compassion for innocent fellow citizens whom he has wrongfully imprisoned, mistreated and imperiled.