SEOUL, Aug. 31 (Xinhua) -- Defense chiefs of South Korea and the United States condemned the Democratic People's Republic of Korea (DPRK)'s recent missile launches during the bilateral talks in Washington, Seoul's defense ministry said Thursday.

South Korean Defense Minister Song Young-moo visited Washington to hold talks with his U.S. counterpart James Mattis at the Pentagon Wednesday morning (Washington time), according to the Ministry of National Defense.

Song and Mattis confirmed a firm South Korea-U.S. alliance, strongly denouncing the DPRK's ballistic missile launch on Tuesday and two other missile tests in July as a reckless, provocative and destructive behavior, the ministry said in a press release.

Pyongyang launched an intermediate-range ballistic missile (IRBM), called Hwasong-12, over the northern Japanese island of Hokkaido earlier this week.

It was followed by the DPRK's tests in July of what it called an intercontinental ballistic missile (ICBM), dubbed by the DPRK as Hwasong-14.

Song and Mattis agreed to continue to strengthen the combined defense readiness of the two allies to defend and deter the DPRK threats by securing core military capabilities and interoperable combat capability.

From this perspective, South Korea's military would continue to develop the Kill Chain and the Korea Air and Missile Defense (KAMD) systems.

The Kill Chain is designed to preemptively strike the DPRK's missile launch sites when signs of the first strike are spotted. The KAMD is a project to develop its indigenous missile defense system to shoot down incoming DPRK missiles at multiple layers.

The defense chiefs expressed their support for the ongoing diplomatic efforts at the denuclearized Korean Peninsula, saying the diplomatic efforts would be backed by strong, effective and trustworthy countermeasures of the military.

They also discussed the conditions-based transfer of wartime operational control of South Korean troops from Washington to Seoul.

The wartime command was handed over to the U.S. forces after the 1950-53 Korean War broke out. South Korea won back its peacetime operational control in 1994.

Also on the dialogue agenda was the revision of the South Korea-U.S. missile guideline, which was first adopted in 1979 to set ceilings on the range of South Korea's homegrown ballistic missiles at 180 km and the payload at 500 kg in return for the U.S. transfer of missile technology to South Korea.

Following the DPRK's ICBM test in late July, South Korean President Moon Jae-in ordered a consultation with the U.S. side on the amendment of the bilateral missile guideline to increase the payload of the country's indigenous ballistic missiles.

Under the revised guidelines, the maximum range and payload for South Korea's ballistic missiles were extended in 2001 to 300 km and 500 kg, and in 2012 to 800 km and 500 kg respectively.

Local media speculations said South Korea would demand the maximum payload of its ballistic missiles be extended to 1 ton.

While discussing the missile guideline revision, the South Korean defense chief mentioned the need for his country to build a nuclear-powered submarine to counter the DPRK's threat of a submarine-launched ballistic missile (SLBM), Yonhap news agency reported citing unnamed government officials.

An unidentified South Korean government official was quoted as saying the issue on the nuclear-powered submarine was raised while talking in principle about what would be the best way to deal with the DPRK's SLBM threat.

Defense Minister Song raised the issue during his parliamentary confirmation hearing in June, saying he was mulling the construction of a nuclear-powered submarine that can pursue the DPRK's submarine equipped with SLBMs.

In August last year, the DPRK test-fired a ballistic missile from a submarine off its east coast. The missile flew about 500 km toward Japan, surpassing the flight distance of 300 km, which South Korea's military regarded as a success.

A complete SLBM technology would raise the DPRK's nuclear threat to a new level as it is very hard to detect and track a DPRK missile from a submarine moving secretly deep under the waters.