South Korea is confronting a growing chasm of distrust with Indonesia, centered around a key joint defense project: the KF-21 fighter jet program. The Southeast Asian nation’s failure to present a payment timetable, as pledged, for its $1.3 billion share of the project’s cost is causing concern in Seoul.

Indonesia’s recent agreements to purchase 42 French Rafale fighter jets for $8.1 billion and 12 used Mirage 2000-5 fighter jets from Qatar for $792 million has raised further questions about its commitment to the KF-21 program, with the future of the joint project in doubt.