SEOUL (Reuters) -- North Korea launched two more ballistic missiles off its east coast on Monday, and the powerful sister of leader Kim Jong Un warned U.S. forces to halt military drills, saying the reclusive nuclear state could turn the Pacific into a "firing range."
The launches come just two days after North Korea fired an intercontinental ballistic missile into the sea off Japan's west coast, prompting the United States to hold joint air exercises with South Korea and separately with Japan on Sunday.
North Korea's state media confirmed the country had fired two projectiles from a multiple rocket launcher, aiming at targets 395 and 337 km (245 and 209 miles) away.
The 600-mm multiple rocket launcher involved in the firing is a tactical nuclear weapon capable of destroying an enemy airfield, state news agency KCNA said.
Japan's Defense Ministry said the two missiles, launched at around 2200 GMT, reached maximum altitudes of about 100 km and 50 km and fell outside Japan's exclusive economic zone.
Japanese Prime Minister Fumio Kishida said he had requested an emergency U.N. Security Council meeting over the tests, and Jiji news agency said the gathering was set for 2000 GMT on Monday.
But prospects for a new round of U.N. sanctions appear slim given the previous vetoes by Russia and China amid the Ukraine crisis and a Sino-U.S. feud over Chinese balloons found in American skies.
South Korea's Joint Chiefs of Staff strongly condemned the launches as a "grave provocation" that should be ceased immediately.
Seoul's Foreign Ministry announced sanctions on four individuals and five entities linked to Pyongyang's weapons programs on Monday over the latest ICBM and missile tests, in what it called its fastest-ever such response to the North's provocations.
"Our government has made it clear that North Korea's provocations will definitely come at a price. Its repeated provocations will result in strengthening South Korea-U.S. deterrence and tightening the global sanctions network," the ministry said in a statement.
The U.S. Indo-Pacific Command said the latest launch did not pose an immediate threat but highlighted the "destabilizing impact" of North Korea's unlawful weapons programs.
U.N. spokesman Stephane Dujarric urged Pyongyang to "immediately desist from taking any further provocative actions" banned under Security Council resolutions and resume denuclearization dialogue.
North Korean leader Kim's sister, Kim Yo Jong, warned against increased presence of U.S. strategic military assets following the joint air drills with its Asian allies over the weekend.
"The frequency of using the Pacific as our firing range depends upon the U.S. forces' action character," she said in a statement carried by KCNA.
The United States and South Korea are set to hold simulated nuclear tabletop exercises aimed at improving operations of American nuclear assets this week, as well as annual springtime Freedom Shield field training in March.
Pyongyang's Foreign Ministry said last week it would respond to the planned exercises with "unprecedentedly persistent, strong counteractions."
"Tension on the peninsula is likely to reach its peak in the coming months, as North Korea is accelerating its military actions with higher frequency, and her statement indicates that it would continue impromptu missile tests using the Pacific as its shooting range," said Yang Moo-jin, a professor at the University of North Korean Studies in Seoul.
Hong Min, a senior fellow at the South's Korea Institute for National Unification, said Kim's mention of the Pacific suggested the North would fire more longer-range missiles more often.
Monday's missile launch is the North's third known weapons test this year, after it fired an unprecedented number of missiles last year, including ICBMs capable of striking anywhere in the United States.
Kim Yo Jong also criticized some South Korean experts who questioned the reliability of the country's ICBM capability, saying Saturday's "sudden" test required nine hours of preparation and calling them "disgusting" and "stupid."
The launch took place "at the most appropriate time," considering weather conditions, and after U.S. and South Korean scout planes went away, she said.
"They had better rack their brains to take measures to defend themselves, instead of doubting or worrying about other's technology," she said. "We affirm once again that there is no change in our will to make the worst maniacs escalating the tensions pay the price for their action."