South Korea on Wednesday test-launched a new ballistic missile that can hit all of North Korea, the president's office said, developed under a new agreement with the United States that lets Seoul extend the weapon's range to up to 800 kilometers (500 miles).

President Park Geun-hye made a rare visit to a missile base on the west coast to watch the launch of the guided missile, which will be a key part of the South's defense against its neighbor's nuclear and missile threat, her office said.

"The test demonstrated improved ballistic missile capability that can strike all parts of North Korea swiftly, and with precision, in the event of armed aggression or provocation," the presidential Blue House said in a statement.

The launch comes a month after the North said it test-fired a submarine-launched ballistic missile. If true, the statement points to progress in the North's missile capabilities, although some experts and U.S. military leaders questioned the authenticity of the North's report.

South Korea's missile is the first developed under new guidelines signed with the United States in 2012 to more than double the range of the South's missiles to tackle its disadvantage with Pyongyang's missile capabilities.

The North has a deployed arsenal of missiles of various ranges and is believed to be developing an intercontinental ballistic missile aimed at delivering nuclear weapons.

In 2012, North Korea successfully launched what is generally considered a long-range rocket, putting what it said was a satellite into orbit. The North called it a space launch vehicle, but the international community said it was a missile that violated U.N. Security Council resolutions.

The North is under various sanctions for its missile and three nuclear tests.

Besides its missile pact with the United States, South Korea has an agreement limiting the range of the missiles and a pact on civil nuclear energy that bars Seoul from developing atomic weapons.