In this handout photo released by the South Korean Defense Ministry, U.S. M270 Multiple Launch Rocket System firing an MGM-140 Army Tactical Missile during a U.S. and South Korea joint missile drill aimed to counter North Korea's intercontinental ballistic missile test on July 5, 2017 in East Coast, South Korea. Getty Images

South Korea is looking to increase its ballistic missile firepower to a 1-ton conventional warhead, but even that is below the amount the North is known to have in its arsenal. The Seoul government reportedly asked for the increase during talks with U.S. officials, suggesting the extra missile payload would help it counter the rising threat from North Korea, South Korea's Yonhap news agency reported Monday. Under a 2012 deal between the U.S. and South Korea, missiles are limited to a range of 800 kilometers (nearly 500 miles) and warheads of 500 kilograms (roughly half a ton). With the bigger warhead, South Korean ballistic missiles could pack more power at a time when the nuclear-armed North Korea is stepping up its own missile development. "That could double the amount of conventional explosives on top, which would allow them (South Korea) to destroy some targets that they currently can't destroy," said Joel Wit, senior fellow at the U.S.-Korea Institute at Johns Hopkins School of Advanced International Studies and co-founder of Washington's 38 North think tank. He said that could include destroying more of the North's "hardened targets like command posts and bunkers."

It comes at a time when the North also is known to be trying to miniaturize its nuclear weapons to fit them to a missile, including a long-range ballistic missile capable of reaching the U.S. mainland. "They're clearly on a path to develop an intercontinental ballistic missile that can reach the United States and to match that with a nuclear weapon," Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, said in remarks at the Aspen Security Forum in Aspen, Colorado. Dunford said the North Koreans today are capable of "a limited missile attack. We are capable of defending against a limited missile attack for our forces in South Korea, our South Korean allies, our Japanese allies, our forces in Okinawa, our forces in Guam, and the American homeland and in Hawaii." At present, South Korea has two U.S.-supplied THAAD anti-missile launchers deployed. There's also a THAAD (or Terminal High Altitude Area Defense) system battery deployed on Guam, where the U.S. military has bases. Japan has Aegis systems in place for missile defense. According to Wit, the North Koreans have about 1,000 missiles of various types that can hit targets in the region, whether South Korea, Japan or Guam. "Some of them might be armed with nuclear weapons but a lot of them will be armed with conventional weapons," he said.

Missiles are driven past the stand with North Korean leader Kim Jong Un and other high-ranking officials during a military parade marking the 105th birth anniversary of North Korea's founding father, Kim Il Sung, in Pyongyang, April 15, 2017. Sue-Lin Wong | Reuters

The U.S. has more than 28,000 troops stationed in South Korea and around 50,000 American personnel in Japan. There also are more than 6,000 troops in Guam. As things stand now, Wit isn't so sure the U.S. has the capability to destroy all the missiles in North Korea or to defend against "large salvos" of rockets. "It would be very difficult if the North Koreans for some reason started launching large numbers of missiles to deal with it," said Wit. "A lot of them would get through." Then again, the Joint Chiefs chairman also said at the Aspen event that there's concern about the ability of North Korea to ramp up its missile capacity and development. He also pointed out that the regime of Kim Jong Un also has stepped up its missile testing and conducted several nuclear tests last year. "Our concern is the growth in capacity that has increased numbers of missiles over time and the combination of an intercontinental ballistic missile and nuclear weapons obviously concern us," said Dunford. The general added, "Do the American people need to be concerned long term? Yes. This is probably at the top of everybody's inbox in national security today ... dealing with the North Korea crisis. But we can protect the American people today and that I am sure." NBC News' chief foreign affairs correspondent, Andrea Mitchell, moderated the discussion with the general and asked how the U.S. does a pre-emptive strike on North Korea when it probably doesn't know where all the weapons are located due to tunnels, underground nuclear facilities and other measures it is believed to take.



She asked about military options planned but Dunford said the U.S. was now focused on a so-called pressurization campaign using primarily economic and diplomatic pressure to denuclearize the Korean Peninsula. Secretary of State Rex Tillerson is working to get the international community to back more of these measures, Dunford said. He added that the U.S. military supports that effort because military options could lead to something perhaps "horrific. It would be a loss of life unlike any we have experienced in our lifetime." Also, the general said he is assuming North Korea already has the ICBM capability. Earlier this month, North Korea test-fired a missile it claimed was a long-range missile capable of reaching the U.S. "In the business I'm in, I get paid to assume that they have that capability now," Dunford said. "So I have a sense of urgency to assume they're going to have it. In my judgment it's academic whether it's six months, 12 months, 18 months or 24 months from now. They're on a path — and it seems a irreversible path — to develop that capability. And so we need to have a sense of urgency to denuclearize the Korean Peninsula, which is our U.S. policy right now."

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