Semtex is a general-purpose plastic explosive containing RDX and PETN. It is used in commercial blasting, demolition, and in certain military applications. Semtex was developed and manufactured in Czechoslovakia, originally under the name B 1 and then under the "Semtex" designation since 1964, labeled as SEMTEX 1A, since 1967 as SEMTEX H, and since 1987 as SEMTEX 10.Originally developed for Czechoslovak military use and export, Semtex eventually became popular with paramilitary groups and rebels or terrorists because prior to 2000 it was extremely difficult to detect,[3] as in the case of Pan Am Flight 103.