Japanese defense planners apparently believe that it pays to think ahead.

The Asahi Shimbun reported on Friday that Japan’s helicopter “destroyer” Izumo had been designed to be an aircraft carrier all along. The newspaper says former Maritime Self-Defense Force (MSDF) executives have confirmed that the warship’s original blueprints called for it to be turned into an aircraft carrier.

“It is only reasonable to design (the Izumo) with the prospect of possible changes of the circumstances in the decades ahead,” a former MSDF executive told Asahi. “We viewed that whether the Izumo should be actually refitted could be decided by the government.”

The 248 meter (814 foot) Izumo is technically classified as a “destroyer” to circumvent current constitutional curbs against building “offensive” military weapons. But it is in most respects a de facto carrier.

Reports say Japan’s military is considering deploying the US F-35B, the maritime vertical takeoff version of the F-35 stealth fighter, aboard the Izumo, which was launched in 2015. The Izumo is the first ship in a class of such Japanese carriers.

Japan’s Defense Ministry had previously denied plans to refit the Izumo as an aircraft carrier.

“The former executive said a consensus was reached privately among the MSDF that the Izumo should be considered for conversion into an aircraft carrier,” Asahi said in its report. “But the MSDF couldn’t explain the need publicly due to the government’s view that aircraft carriers capable of launching large-scale attacks are equivalent to the military capability prohibited by the war-renouncing Article 9 of the Constitution.”

Japan’s Yomiuri Shimbun reported last week that the government may buy up to 40 F-35B fighters from the US that can operate from helicopter carriers, island bases and commercial airports.