This unprecedented decision to shun visible connection with the military is prompted largely by anti-American sentiments in parts of the Muslim world where many groups operate, aid agencies say.
"God help us if we become identified as one of the belligerents," CARE security chief Bob McPherson, a former US Marine colonel in Somalia, said by telephone from Jordan.
To a guerrilla with a gun, the brutally random nature of modern warfare has blurred the line between helpful humanitarian and enemy interloper. The rocky marriage of private relief groups and multinational armies in Bosnia, Kosovo and Somalia may have ended in divorce in Afghanistan, when armed US soldiers in civilian clothes were distributing aid.
"That increased our security risk considerably," said Mark Bartolini, Middle East director for the International Rescue Committee. "You will see the vast majority of (relief groups) keeping their distance from the military. This is a highly controversial war."