"The [seventh] missile sends a very loud message to the rest of the world that it [North Korea] will act on its own and will act in defiance of the UN resolution against it [passed in 2006 when the North tested its first nuclear weapon].
"The question now is: how will the international community react? We are hearing condemnation from the region: Japan, South Korea; we have yet to hear very clearly from the US.
"Over the past few days China and a lot of other nations have been pushing for a diplomatic solution, but North Korea has been silent in recent days and they have only been talking with missiles."
North Korea test-fired four short-range anti-ship missiles from the same site on Thursday, triggering protests on Friday in Seoul, where anti-North Korean activists burned mock-up missiles and images of the North Korean leader, Kim Jong-il.
"This really will be seen as a provocation directed at South Korea, mainly because the Scud has a range of 500km, which basically could hit many major cities in the South," our correspondent said.
In a statement, South Korea's joint chiefs of staff said: "Our military is fully ready to counter any North Korean threats and provocations based on strong South Korea-US combined defence posture."
North Korea's state news agency carried no reports on the latest launches.
US forces in the region had been ready for the missile tests, Admiral Gary Roughead, the chief of US naval operations, said.
"Our ships and forces here are prepared for the tracking of the missiles and observing the activities that are going on," Roughead said after meeting Japanese military officials in Tokyo on Saturday.
The Japanese government condemned the North's action.
The launch "is a serious act of provocation against the security of neighbouring countries, including Japan, and is against the resolution of the UN Security Council", Takeo Kawamura, the Japanese chief cabinet secretary, said in a statement.
"It looks like North Korea is trying to attract attention of the international community and also demonstrate its power in the region"
Leonid Petrov, North Korea specialist
The statement also urged North Korea to suspend all missile development activities.
Leonid Petrov, a North Korea specialist from the School of Pacific and Asian studies at the Australian National University, told Al Jazeera that the missile launches were an attention-grabbing ploy by the North.
"It looks like North Korea is trying to attract attention of the international community and also demonstrate its power in the region," Petrov said.
North Korea had previously warned that it would conduct military drills on its eastern coast and had issued a no-sail zone in waters off its east coast through July 10.
"There's been no question that over the last few days there's been a lot of concern about how many tests North Korea would conduct in terms of missiles," Al Jazeera's Chao said.
"South Korea has already announced that it will increase its defence spending in the next few years, in terms of missile protection and nuclear protection and protection against a lot of other attacks from the North."
In April, North Korea launched a rocket that boosted its long-range missile capability followed by a nuclear test – the second since 2006 – on May 25 that put it closer to having a working atomic bomb.
Shortly after the atomic test, Pyongyang fired a total of six short-range missiles, renounced the truce in force on the Korean peninsula for half a century and threatened possible attacks on Seoul.
The UN last month approved tougher sanctions against North Korea following the May nuclear test, but the North responded by vowing to strengthen its nuclear arsenal.