No “Enhanced Radiation Warheads” currently in the U.S. arsenal. Other western countries have also built a couple (esp France), but have scrapped them during the 1980’s or at the end of the Cold War. One of the U.S. applications were SAMs like the Standard series or Sprint; the other applications was short-range battlefield ballistic missiles like the Lance.
China might be the only country fielding such a warhead today – the warhead of the DF-31 is said to be jazzed-up copy of the W-70 warhead which is said to have been stolen by China from the LLNL (see the link “House.gov – Cox Report”).

http://www.nuclearfiles.org/reatomicbasics/020109neutronbomb.htm
http://www.airpower.maxwell.af.mil/airchronicles/aureview/1979/jul-aug/snow.html
http://taiwansecurity.org/NYT/NYT-990514.htm
http://www.house.gov/coxreport/cont/gncont.html