'Begging for war': UN council weighs North Korea sanctions as U.S. monitors

Nikki Haley, Ambassador to the United Nations

South Korea on Monday fired missiles into the sea to simulate an attack on the North's main nuclear test site, as the U.S. urged the United Nations to step up pressure on Kim Jong Un and accused him of "begging for war."

A day after Kim's regime detonated its largest ever nuclear test explosion, South Korea's Defense Ministry said its neighbor appeared to be planning another future missile launch -- possibly of an intercontinental ballistic missile -- to show off its claimed ability to target the U.S. with nuclear weapons.

South Korea's military said its live-fire exercise was meant to "strongly warn" Pyongyang. The drill involved F-15 fighter jets and the country's land-based "Hyunmoo" ballistic missiles firing into the Sea of Japan.

The target was set considering the distance to the North's test site and the exercise was aimed at practicing precision strikes and cutting off reinforcements, Seoul's Joint Chiefs of Staff said.

As tensions escalated, U.S. Ambassador to the U.N. Nikki Haley told a Security Council meeting: "Enough is enough ... we must adopt the strongest possible measures."

She added: "We have kicked the can down the road long enough. There is no more road left."

Kim's "abusive use of missiles show that he is begging for war," Haley said, adding that proposals for a mutual freeze in military exercises, as suggested by China, were "insulting."

Earlier, Chang Kyung-soo, an official with South Korea's Defense Ministry, told lawmakers Monday that Seoul was seeing preparations in the North for an ICBM test, but didn't provide details about how officials had reached that assessment, The Associated Press reported. Chang also said the yield from the latest nuclear detonation appeared to be about 50 kilotons, which would mark a "significant increase" from North Korea's past nuclear tests.

However, a South Korean military official told NBC News that Chang's briefing "was pointing out that North Korea is always ready for the next ballistic missile launch and this does not mean that the South Korean military is expecting another ballistic missile launch at a given set time."

China also warned North Korea against launching another ballistic missile, saying it should not worsen tensions.