South Korea's defense ministry vowed Wednesday to speed up building an integrated air and missile system, and secure missile capability to hit all parts of North Korea to counter threats from North Korea, which is building up its nuclear arsenal.

Seoul has been making efforts to improve its missile capacity following the revision of a missile guideline in October 2012, but calls for improved security measures have heightened after Pyongyang launched a long-range missile and conducted its third atomic test recently despite a chorus of international condemnation.

In a show of protest, the defense ministry said it has deployed indigenous cruise missiles capable of hitting all parts of North Korea and will soon reveal more details.

"The South Korean military has secured various combat capabilities, including cruise missiles and ballistic missiles, to cope with North Korea's threat," ministry spokesman Kim Min-seok said in a briefing.

According to officials, the Navy has installed ship-to-land cruise missiles with a range of 500-1,000 kilometers on its Aegis warships and destroyers. South Korea's Navy chief earlier announced that the deployment will be completed in the next couple years to be able to strike nuclear and missile arsenals.

The military will also accelerate the process to develop an advanced missile interception system, the so-called "kill chain," which is designed to detect, target and destroy missiles. The system mobilizes spy satellites and surveillance aircrafts as well as missile and fighter jets to detect incoming targets and destroy them in the air.

While the military had initially planned to complete the missile defense system by 2015 to coincide with Seoul regaining its wartime operational control of its troops from Washington, the recent atomic test is expected to accelerate the process for early deployment.

The U.S. stations 28,500 troops in South Korea and provides a "nuclear umbrella" for its ally, limiting Seoul's nuclear and missile capability as part of a non-proliferation campaign.

In addition, the military will push to adopt a military spy satellite by 2021 to put closer tabs on the communist country and integrate with its own missile defense shield program, dubbed the Korean Air and Missile Defense (KAMD).

South Korea currently operates Arirang-3, a multipurpose satellite, which provides geographical information on the Korean Peninsula, including North Korea's missile and nuclear test sites.

However, it still relies on the United States for much of its intelligence due to the commercial satellite's limited vision and longer rotation period.

With adding reconnaissance satellites to its monitoring capabilities, the military hopes to increase its surveillance of major North Korean military facilities to better anticipate aggressive actions by the communist state.

As the North warned of additional measures against the U.S. and its allies that denounced Tuesday's atomic test, military officials remain on high alert whether it will carry out additional tests or launch provocations with missiles or artillery.

"The military is preparing various kinds of provocations, including an artillery bombardment, infiltration across the border and attacks against major government facilities," Kim said.

As the reclusive country is believed to have prepared underground tests at two of the three tunnels, South Korea and U.S. forces are closely monitoring the Punggye-ri test site to detect signs of an additional test, while mobilizing a radiation detection airplane to collect air samples from the test site to determine fission materials.

"(The North) has completed all preparations to carry out another test at any time, and another test is possible without further preparations," Kim said, without giving further details.

Seoul's defense ministry determined the magnitude of the latest explosion was bigger than those of the previous tests, but it still fell short of atomic bombs detonated in Japan.

The yield of the 2006 test has been estimated at less than 1 kiloton, equivalent to 1,000 tons of TNT, and the second at some 2-7 kilotons. A Nagasaki-type bomb is estimated to have a 20 kiloton yield.

"Although North Korea announced that it succeeded in making a smaller and lighter bomb, we still doubt whether it mastered the technology," Kim said. "It would take time to achieve the goal."

As Pyongyang claimed it had used a "miniaturized" and lighter nuclear device, some suspect it again used plutonium, which is suitable for use as a missile warhead. If it turns out the test used a new uranium-based weapon, it would show that the North has made more progress in its highly enriched program, which would provide a second route to expand the isolated nation's nuclear arsenal. (Yonhap News)