Prime Minister Shinzo Abe on Wednesday called for strengthening Japan's defense capabilities in new fields such as cyberspace and outer space, citing the rapidly changing security situation surrounding the country.

"It is impossible to protect our country from every threat if our thinking is limited to conventional categories of land, sea and air," Abe said during a meeting of a governmental advisory panel on reviewing national defense buildup guidelines.

"It will be especially vital for Japan to maintain an advantage in the new realms," he said, referring to space and cybersecurity.

The first meeting of the panel, consisting of defense and diplomatic experts and scholars, was held a day after the Defense Ministry released its annual white paper which pointed out that North Korea's nuclear and missile programs remain a serious threat to Japan despite the historic U.S.-North Korean summit in June.

The ministry is seeking to compile a revised version of the National Defense Program Guidelines based on debates by the panel and gain the Cabinet's approval by the end of this year.

The guidelines, which were last approved in December 2013, set defense capability targets that Japan should achieve over the next decade.

In the meeting, Abe said the security environment facing Japan has become severe and uncertain "at a much faster speed" than five years ago.

He has instructed Defense Minister Itsunori Onodera to review the current guidelines in the face of security challenges including North Korea's development of nuclear weapons and missile threats and China's growing military power.

The ministry is also planning to work out the Mid-Term Defense Program, which specifies a five-year defense spending and procurement plan, by the end of the year.

The nine-member panel headed by Akio Mimura, chairman of the Japan Chamber of Commerce and Industry, is scheduled to meet every two or three weeks by early December.

Ryozo Kato, Japan's former ambassador to the United States, Shigeru Iwasaki, a former chief of staff of the Self-Defense Forces, and Shinichi Kitaoka, a politics scholar and president of the Japan International Cooperation Agency, are among the panel members.