The new range could cover the entire peninsula and enable Seoul to better respond to perceived missile threats from the DPRK.
Critics say South Korea's extension plan contradicts its commitment to a global arms control agreement, the Missile Technology Control Regime (MTCR), which aims to curb the spread of missiles and unmanned aerial vehicles that could deliver weapons of mass destruction.
The White House on Sunday defended South Korea's pursuit of longer-range missiles as "absolutely legitimate to respond to a threat posed by the DPRK's ballistic missile program."
