Lockheed Martin's F-35 fighters are the best choice for Japan's future operational needs, the nation's highest-ranking uniformed officer said on Wednesday, in a vote of confidence for the state-of-the-art US warplane. His comments follow reports that some nations that have placed orders for the F-35s may reconsider their plans. Shigeru Iwasaki, chief of the Japanese Self-Defence Forces' Joint Staff, also said advancement of North Korea's arms technology in a series of nuclear and missile tests posed a serious threat to Japan, but its missile defence system should provide the country with sufficient protection. "When I was the head of the air force, I spearheaded the decision (to procure F-35s). Or, rather, we drew up a plan, which was then approved by defence minister," said Iwasaki, a veteran fighter pilot who used to fly F-15s, Japan's current mainstay combat aeroplane. "There were various candidates. But I still believe the F-35 is the best fighter, when we think about Japan's future national security," he said in an interview with Reuters. Dutch orders for F-35 warplanes are likely to be cut back, sources close to the discussions told Reuters last week, citing cost overruns and delays in the programme, uncertainty over the Netherlands' defence strategy and budget cuts across Europe. US officials fear cuts in orders by the Dutch or other buyers could trigger a "death spiral" in the Pentagon's biggest arms programme by driving up the price of remaining orders, leading to more cancellations. Japan, one of the closest US allies in Asia, has remained steadfast in its plans to buy 42 F-35s, with the first four planes scheduled for delivery by March 2017. Iwasaki described North Korea's nuclear and missile tests as "unforgivable". North Korea conducted its third nuclear test in February although it is not believed to have acquired weapons capability. But it has threatened US naval bases in Japan, which are within the range of its medium-range missiles. Iwasaki said, however, Japan was sufficiently protected by its missile defence system, equipped with Standard Missile-3 (SM-3) interceptors and Patriot Advanced Capability-3 (PAC-3) interceptors. SM-3 interceptors are capable of shooting down a ballistic missile outside the earth's atmosphere, while PAC-3 interceptors provide back-up protection as the missile returns to earth. On Japan's tense ties with China, Iwasaki urged Beijing to agree to reopen talks with Tokyo on the establishment of a hotline and other maritime communication channels to avoid any unintended military clash between Asia's two biggest economies. Japan has been locked in a territorial dispute with China over a group of East China Sea islets, known as the Senkaku in Japan and the Diaoyu in China.