South Korea and the United States will consider deploying US strategic military assets to the South permanently on a rotational basis to strengthen the US "extended deterrence" protection of the Asian ally from nuclear and missile threats from North Korea, Seoul's defense chief said Thursday.

South Korean Defense Minister Han Min-koo made the remark after talks with US Defense Secretary Ash Carter. Deployment of strategic assets, such as B-2 stealth bombers, would significantly back up repeated pledges by the US to mobilize all military capabilities, including nuclear weapons, to defend the South.

"We discussed a lot of options, including permanently deploying US strategic assets on a rotational basis," Han said during a joint news conference with Carter at the Pentagon. "We'll conduct a review (of options) going forward, including those ones."

Permanently deploying US strategic assets on a rotational basis means keeping at least one such asset either in, over or off in South Korea at any given time. Such deployment would not only reassure South Koreans of the US defense commitment, but serve as a strong warning and deterrent to North Korea leader Kim Jong-un.

The US has temporarily sent strategic assets, such as nuclear-capable B-52 and B-1B bombers, F-22 stealth fighter jets and nuclear-powered, cruise-missile submarines, to South Korea in a show of force in the wake of the North's two nuclear tests and a series of missile launches, but perceptions have grown among South Koreans that such one-off missions are not enough.

Carter said the two sides "discussed a number of ways that extended deterrents can be further strengthened."

"No one should have any doubt about this. We have today the capabilities for extended deterrence ... The full weight of our alliance capabilities including all US capabilities and they're very strong, very robust, very ready," he said. "We are, however, talking about a number of measures, and you named one, to further enhance deterrence."

"Extended deterrence" refers to the commitment to use nuclear weapons, if the need arises, to deter attacks on allies. The US has provided extended deterrence and the "nuclear umbrella" to South Korea after withdrawing nuclear warheads from the country in the early 1990s.

Ensuring the commitment's implementation was a key focus in Thursday's annual defense ministers' talks, known as the Security Consultative Meeting, amid heightened security concerns in South Korea in the wake of the North's fifth nuclear test and a series of ballistic missile launches.

In Wednesday's "two plus two" alliance talks that brought together their foreign and defense ministers, the two sides also agreed to established a high-level dialogue, known as the "Extended Deterrence Strategy and Consultation Group," to discuss how to carry out US extended deterrence.

"The United States remains committed to defending our allies against any threat with the full spectrum of American military might. That's why we're adapting our force structure on the peninsula, mostly recently by agreeing as allies to deploy THAAD to defend against North Korean missile threats," Carter said during a joint news conference with Han.

"The United States is reaffirming its ironclad commitment to defend South Korea with our extended deterrence capabilities," he said. "Make no mistake. Any attack on American or our allies will not only be defeated, but any use of nuclear weapons will be met with an overwhelming and effective response."

Carter also condemned North Korea's latest test of its Musudan intermediate-range missile the previous day, saying the test, even if a failure, is a violation of UN resolutions. The latest launch, which came Thursday morning (Korean time), marked the second time the North has tested the missile in less than a week. The previous test on Saturday also failed.

Han said he believes the North will continue testing the missile until it's successful. He also said that there was a high possibility that North Korean leader Kim Jong-un was at the site when the launch occurred.

After the talks, the two sides also issued a joint communique saying that Carter and Han agreed to "to examine options to take additional steps that further strengthen extended deterrence capabilities to ensure that North Korea has no doubt about Alliance resolve."

"The Secretary and the Minister reaffirmed that any North Korean aggression or military provocation is not to be tolerated and that the United States and the Republic of Korea would work shoulder-to-shoulder to demonstrate our combined resolve," the communique said.

The two countries also reaffirmed their commitment to THAAD's deployment in South Korea.

"The secretary and the minister emphasized the military effectiveness of THAAD and reaffirmed that the system is aimed solely at defending against North Korean missile threats and would not be directed towards any third party nations," the communique said.

The two sides also agreed to increase naval cooperation to respond to the North's maritime provocations, including the submarine-launched ballistic missile test launches, the communique said.

"The secretary and the minister committed to consider various cooperation measures to expand the scope and execution of the ROK-US naval training events, including combined ballistic missile defense and anti-submarine exercises, and to increase information-sharing through strengthened staff coordination," it said. (Yonhap)