tokyo japan consider refit izumo helicopter carrier land u.s. marines f-35b stealth fighters government source say tuesday tokyo face china maritime expansion north korea missile nuclear development japan fully fledge aircraft carriers since world war two defeat 1945. refit izumo would aim prepare scenario runways japan destroy missile attack bolster defense around japan southwestern islands china maritime activity increase three government source close matter say japanese government keep sight possible future procurement f-35b fighter jet take land vertically look remodel izumo 248-metre 814-feet izumo japan large warship equip flat flight deck design eye host f-35b fighters elevator connect deck hangar carry aircraft source say possible refit measure include add curve ramp end flight deck improve deck heat resistance jet burners reinforce ship air traffic control capability say however japanese defence minister itsunori onodera say government take concrete step towards refit izumo regard defense posture constantly conduct various examinations concrete examination way introduction f-35b remodel izumo-class destroyers onodera tell reporters tuesday izumo sister ship call kaga japan frequently conduct joint drill u.s. aircraft carriers recent months boost deterrence north korea one three government source call exercise great opportunity see eye u.s. military operate aircraft carriers japan look possible conversion izumo aircraft carrier regional tension soar since north korea conduct sixth large nuclear test september pyongyang say month late successfully test new intercontinental ballistic missile could reach u.s. mainland japan also wary china long-range missiles would like secure measure launch fighters aircraft carriers case runways operate u.s. force japan japan air self-defence force destroy missiles article japan pacifist constitution take literally ban maintenance arm force however japanese governments interpret allow military exclusively self-defense own aircraft carrier could raise question constitutionality source say government set address issue new national defence programme guidelines compile end 2018. japan consider refit helicopter carrier stealth fighters government source