Roughing up of a Pakistani citizen by three Americans at Aabpara, Islamabad, and arrest of four Americans in possession of assault rifles without identity marks show the Black Water death squads have landed. Gentlemen welcome We had heard a lot about you and your expertise in torture that you wantonly practiced in Abu Graib (Iraq) and Bagram (Afghanistan). But arent you guys a little early because the new imperial fortress of an embassy for you to disappear into after the action is not yet complete? -MEHRAN LEGHARI, Lahore, via e-mail, September 3.