"Since the Cold War ended, the national security situation facing Japan has changed dramatically," Abe said at a ceremony to mark the creation of a cabinet-level defense ministry to replace the previous defense agency.

He said the move "shows the maturity of Japan's democracy".

"This is a significant step for us to get out of the post-war regime and lay the foundations for our efforts to build the nation," he added.

Abe, a passionate advocate of a more assertive Japan, has faced slipping poll ratings since taking office in September with a vow to build "a beautiful nation" and calls for a hard line against North Korea's nuclear program.

He has sought to repair frayed ties with China, which was angered by former prime minister Junichiro Koizumi's repeated visits to a Tokyo war shrine seen by critics as a symbol of Japan's past military aggression.

China urged Japan to continue its peaceful post-war policies after the creation of the ministry.

"We feel that if Japan maintains its direction of peaceful development, it is in line with Japan's own basic interests," Foreign Ministry spokesman Liu Jianchao told a regular press briefing.

"We also hope that whatever structural changes Japan makes it can continue on the path of peaceful diplomacy."

Japan's parliament enacted laws in December to create the full defense ministry and to instill patriotism at schools, breaking two taboos lingering since defeat in World War II.

The change is partly symbolic but the ministry will also have more power than the previous defense agency because it can submit its own budget requests.

Fumio Kyuma, until now the director-general of the defense agency, takes the title of defense minister. Japanese troops are still to be called the "Self-Defense Forces".

"The security situation surrounding Japan remains severe," said Kyuma, referring to North Korea's test missile launches in July and its first nuclear test in October.

The bill enjoyed wide support, with the largest opposition party joining the ruling coalition.

But the leader of the smaller Social Democratic Party, Mizuho Fukushima, criticized the move, saying it would enable Japan to send troops abroad to support the US military as soon as the post-war constitution is revised.

Previous attempts to create a defense ministry stalled over political sensitivities in light of Japan's past aggression and fears of upsetting neighboring countries.

Despite its official pacifism, Japan has one of the world's biggest military budgets at 4.81 trillion yen (41.6 billion dollars) a year.

Japan has steadily been assuming a more visible military presence to counter its post-war image as solely an economic power.

In a groundbreaking move, Japan sent troops on a reconstruction mission to Iraq, the first time since 1945 that it had deployed to a country where fighting was underway.

Japan also provides offshore refueling services for the alliance in its mission in Afghanistan.

In an interview with the BBC, Abe said other nations had nothing to fear from a more assertive Japan.

"I believe we will be able to gain the understanding as well as the confidence of the world regarding Japan's assertiveness," he said.

Abe left Tuesday on his first trip to Europe where he will seek to strengthen ties with NATO and galvanize support for a hard line against North Korea.

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