between 2 sides before establishing diplomatic relationship, which said two sides agreed to postpone final or unilateral solution to the dispute:

japan controlled it de facto, china didn't object. but both sides must do the things silently. japan allowed no own citizen to it; china (and taiwan later also) also disallowed any1 to land. this made it actually a desolated place, no development at all.

japan might deny this agreement now, but then how it explained that why japanese citizens are disallowed to land on it?