Could Japan be gearing up to equip its already formidable submarines with long-range strike systems and cutting-edge power sources?

That's what an expert panel has recommended to help boost deterrence as security tensions in Asia run high and Tokyo’s neighbors rapidly upgrade their military capabilities.

Established in February last year to review the progress of revisions to Japan’s key security documents, the panel has used a recent report to call for the development of submarines armed with “long-range missiles” that can be launched vertically.