Byron has recently signed a deal with Ashdown Amps for equipment of the ABM range. Minuteman ICBMs, and the LIM-49 Spartan ABM. In 1971 work starting on the next generation of ABM systems - A135. In 1970 serious efforts to explore the ABM problem started. Other projects include SAM and ABM defenses. AMD calls this pair of instructions "Advanced Bit Manipulation" (ABM). Scheduled service to Antigua is provided by FlyMontserrat and ABM Air. A modified two-tier Moscow ABM system is still used. Other countries were also involved in early ABM research. Calibration plays a pivotal role in both CA and ABM simulation and modelling approaches. HQ-9 may have some ABM capability. Testing ABM technology continued during the 1990s with mixed success. Further work was cancelled as US ABM policy changed. Project 640 had been the PRC's indigenous effort to develop ABM capability. These defects made the Mk-2 overly susceptible to anti-ballistic missile (ABM) systems.