Japan's Fumio Kishida says his country urgently needs to strengthen its military capabilities amid a worsening security environment in the East and South China seas, and threats from North Korea's nuclear and missile advancement
At the international fleet review hosted by Japan, Prime Minister Kishida said on Sunday Russia's war on Ukraine was also a major concern.
Eighteen warships participated in the review from 12 countries, including the United States, Australia, Canada, India, New Zealand, Singapore and South Korea, while the US and France also sent warplanes.
South Korea joined for the first time in seven years, in the latest sign of improvement in badly strained ties between Tokyo and Seoul over Japan's wartime atrocities.
"The security environment in the East and South China seas, especially around Japan, is increasingly becoming more severe," Kishida said, noting North Korea's increased missile firings, including one that flew over Japan last month, and growing concern about the Russian invasion's impact in Asia.
Avoiding disputes and seeking dialogue is important, Kishida said, but it is also necessary to be prepared for provocations and threats to peace and stability.
He repeated his pledge to significantly reinforce Japan's military capability within five years.
Kishida said Japan urgently needs to build more warships, strengthen anti-missile capability and improve working conditions for troops.
"We have no time to waste," Kishida said after his review aboard JS Izumo, where naval officers from the participating countries gathered to review a demonstration of the frigates, submarines, supply ships and warplanes in Sagami Bay southwest of Tokyo.
The 248metre-long Izumo has been retrofitted so that it can carry F-35Bs, stealth fighters capable of short take-offs and vertical landings, as Japan increasingly works side-by-side with the US military.
Kishida said Japan will further strengthen the deterrence and response capability of the Japan-US alliance.
Later Sunday, Kishida was to visit the USS Ronald Reagan, the US Navy's only forward-deployed aircraft career, off the US naval base of Yokosuka, with US Ambassador to Japan Rahm Emanuel.
Japan has steadily stepped up its international defence role and military spending over the past decade, and plans to double its military budget in the next five to 10 years to about 2 per cent of its GDP, citing a NATO standard, amid threats from North Korea and China's growing assertiveness.
Kishida's government is currently working on a revision to its national security strategy and mid- to long-term defence policies, and is considering allowing the use of pre-emptive strike capability in a major shift to Japan's self-defence-only postwar principle.
Critics say allowing pre-emptive strike capability could violate Japan's pacifist Constitution.
Apparently addressing concerns from Asian neighbours, Kishida said Japan will stick to its postwar pledge as a "pacifist nation" and continue to explain its security policy to gain understanding, while asking other countries to do the same.
Many Asian countries, including South Korea, were victims of Japanese aggression in the first half of the 1900s, and an attempt by Japan to increase its military role and spending could be a sensitive issue.
Sunday's international fleet review marks the 70th anniversary of the founding of Japan's post-war navy, called the Maritime Self-Defence Force, seven years after Japan was demilitarised after its World War II defeat.
The naval ships and warplanes were to participate in joint exercises later on Sunday and Monday.
It was the first time Japan hosted an international fleet review in 20 years.
China did not take part in the review but is to participate in the two-day Western Pacific Naval Symposium to be held in Yokohama from Monday.