Tokyo’s recent decision to block refueling support for the ROK Air Force’s Black Eagles and Seoul’s decision to postpone a joint naval search and rescue drill scheduled later this month reveal the structural fragility of ROK-Japan defense cooperation.

The episode exposes how vulnerable the relationship remains to nationalist triggers at a moment when the strategic cost of instability has sharply increased for both governments and for the U.S.

The events involved limited military value in operational terms, but they demonstrate how narrow the margin has become for maintaining continuity in bilateral coordination and how easily routine arrangements can collapse when