Sejil, or Sejjil, (lit. 'brimstone') is a family of Iranian solid-fueled medium range ballistic missiles. The Sejil are replacements for the Shahab liquid-fueled ballistic missiles. The missile utilizes composite solid fuel and unlike the Shahab-3 medium-range ballistic missile (MRBM), which is launched only vertically, the Sejil could be launched at a variable angle. As a weapon, Sejil presents much more challenge to Iran's potential enemies, as solid-fuel missiles can be launched with much less notice than liquid-fueled missiles, making them more difficult to strike prior to launch.