SEOUL, South Korea — North Korea's weekend missile launches show the communist country is improving its capability and accuracy and are a cause for concern, officials said today.

North Korea launched seven ballistic missiles into waters off its east coast Saturday in a show of military firepower that defied U.N. resolutions and drew international condemnation and concern. It also fired four short-range missiles Thursday believed to be cruise missiles.

South Korea's Yonhap news agency — citing a South Korean government source it did not identify — reported that five of the seven ballistic missiles landed in the same area, indicating their accuracy has improved.

Australian Foreign Minister Stephen Smith said North Korea's capabilities were getting better.

"If you look at their most recent efforts, the most worrying thing is not their current capacity in terms of distance or scope but how they have improved," he told the Nine Network.

"We have seen improvements regrettably in their technology and their approach," he said, emphasizing the latest missile tests were clearly a provocative act aimed at the U.S.

Saturday's launches on U.S. Independence Day appeared to be a slap 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. The display was similar to one that took place three years ago, also while Americans celebrated the Fourth of July during another period of tensions over Pyongyang's nuclear weapons program.

An official, speaking on condition of anonymity citing department policy, said the Defense Ministry was investigating the launches and it would take about a week to complete an analysis.

He also said no signs of additional missile launches had been detected, but more were possible given North Korea warned ships to stay away from the area through July 10.

North Korea's state news agency did not mention the launches. In Washington, the White House had no immediate comment. But two senior officials in President Barack Obama's administration, speaking in advance of the launches, said any reaction was likely to be muted to avoid giving attention to Pyongyang or antagonize it. They spoke on condition of anonymity because they were not authorized to discuss the matter publicly.

South Korea said Saturday that the missiles likely flew more than 250 miles, apparently landing in waters between the Korean peninsula and Japan.

South Korea and Japan both condemned the launches, with Tokyo calling them a "serious act of provocation." Britain and France issued similar statements.