Pyongyang launched seven missiles into waters off its east coast Saturday in a show of force that defied U.N. resolutions and drew international condemnation.
On Monday, South Korea's mass-circulation Chosun Ilbo newspaper reported the launches were believed to have included three Scud-ER missiles with a range of up to 620 miles.
The paper said the Scud-ER has a longer range and better accuracy compared with previous Scud series so is "particularly a threat to Japan."
Tokyo is about 720 miles from the base on North Korea's east coast from where the missiles were fired. Some other parts of Japan are closer, well within the range of a Scud-ER.
Scuds are single stage, liquid-fueled missiles, originally developed in the former Soviet Union, and generally known for poor accuracy. Ballistic missile programs in Pakistan and Iran were built on Scud technology.
The Chosun Ilbo, citing a government source it did not name, said the other four missiles were two Scud-C missiles with a range of 310 miles and two medium-range Rodong missiles that can travel up to 810 miles.
Five of the seven missiles flew about 260 miles (420 kilometers) from an eastern coastal launch site and landed in one area, meaning their accuracy has improved, the paper said.
South Korea's Defense Ministry spokesman Won Tae-jae said Monday that the North demonstrated improved missile accuracy in the latest tests because they all landed in the same area.
He declined to confirm details of the Chosun Ilbo report.
Another ministry official told The Associated Press on Sunday that the missiles appeared to have traveled about 250 miles, meaning that key government and military facilities in South Korea were within range. The official spoke on condition of anonymity citing department policy.
North Korea has long-range missiles as well. The Taepodong-2 has a potential range of more than 4,100 miles, putting Alaska within striking distance.
The country is believed to be developing a missile with an even longer range that could potentially put the U.S. west coast, Hawaii, Australia and eastern Europe within striking distance.
The launches on July 4 the U.S. Independence Day holiday also appeared to be a poke at Washington as it moves to enforce U.N. as well as its own sanctions against the isolated regime for its May 25 nuclear test.
Adm. Mike Mullen, chairman of the U.S. Joint Chiefs of Staff, warned they were "very destabilizing, potentially."
North Korean state media have not specifically mentioned the launches but boasted Sunday that the country's military could impose "merciless punishment" on those who provoke it.
"Our revolutionary forces have grown up today as the strong army that can impose merciless punishment against those who offend us," the North's main Rodong Sinmun newspaper said in a commentary carried by the official Korean Central News Agency.
The North has engaged in a series of acts this year widely seen as provocative. It fired a long-range rocket it said was a satellite in early April, and in late May it carried out its second underground nuclear test following the first in late 2006.
The U.N. Security Council punished Pyongyang with tough sanctions centered on clamping down on North Korea's alleged trading of banned arms and weapons-related material.
because of suspicions it may be carrying illegal weapons, possibly to Myanmar. The ship, however, turned around a week ago without stopping at any port and headed toward home.
Won, the Defense Ministry spokesman, said the Kang Nam 1 was expected to arrived in the North later Monday.
Separately, in Kuala Lumpur, Malaysian Foreign Minister Anifah Aman pledged to work with the U.S. to block North Korea from using the Southeast Asian nation's banks for any weapons deals.
The assurance came as U.S. envoy Philip Goldberg, in charge of coordinating the implementation of sanctions against Pyongyang, met with Malaysian officials in Kuala Lumpur.
South Korean media have reported that North Korea sought payment through a bank in Malaysia for a suspected shipment of weapons to Myanmar.