South Korea developed ballistic Missile to counter North Korea

South Korea on 4 April 2014 developed a ballistic missile capable of striking most of North Korea. The missile was launched from a test site in Taean, a coastal town southwest of Seoul.
The test came a day after North Korea raised tensions by test-firing 30 short-range rockets off its east coast on 22 March 2014. 
The new missile with a range of 310 miles (500 Km) is able to carry a warhead of up to one-tonnes.
The missile was developed under an agreement of 2012 with the United States. Under the agreement, South Korea decided to almost triple the range of its ballistic missile systems.

South Korea is developing new missiles since Washington and Seoul revised their defence treaty in 2012. Under the defence treaty, it was decided to extend the range of South Korea’s ballistic missiles from 186 to nearly 500 miles to cope better with North Korea’s increasingly sophisticated missile and nuclear programs.
The tensions between the two Koreans have risen in recent weeks despite some signs of thaw between the two nations in February 2014. In February 2014, the two rivals held the first reunion in more than three years for families divided by the 1950-53 Korean War.
Even when annual South Korean-US military exercises began at the end of February, the protests from Pyongyang were relatively muted, and there was talk of further high-level meetings and greater cooperation.