New Zealand is weighing the purchase of advanced warships from Japan or the U.K. to modernize its aging fleet and bolster its defense capability.The South Pacific nation, member of the Five Eyes intelligence-sharing network alongside Australia, the U.S., the U.K. and Canada, is focused on Japanese Mogami-class or the U.K.’s Type 31 frigates.Discussions are under way with the Royal Australian Navy and the U.K.’s Royal Navy about the frigate replacement and ongoing service arrangements, Defense Minister Chris Penk said Thursday in Wellington. New Zealand’s two current frigates were commissioned in 1997 and 1999.