Three Indonesian Islands Shared with Neighbors: Timor, Borneo, New Guinea

Indonesia's 17,000+ islands include three giants split by international borders:

1. Timor (Shared with Timor-Leste)

• West Timor (Indonesia, East Nusa Tenggara province) — capital Kupang.
• East Timor → independent Timor-Leste since 2002 (capital Dili).
• Border settled 2019 (maritime boundaries pending).

2. Borneo (Shared with Malaysia & Brunei)

• Kalimantan (Indonesia) — 73 % of island, 5 provinces.
• Sarawak & Sabah (Malaysia) — 26 %.
• Brunei — 1 % (two enclaves).
• Border treaties 1960s–2010s; some maritime claims unresolved.

3. New Guinea (Shared with Papua New Guinea)

• Western New Guinea (Indonesia) — Papua, West Papua, Central Papua, South Papua, Highland Papua provinces.
• Papua New Guinea (independent 1975) — eastern half.
• Border: 141st meridian east (land) + Fly River / Star Mountains (complex).

Why It Matters

• Resource governance (gold, copper, gas, timber).
• Indigenous peoples cross borders (Asmat, Dani, highland groups).
• Security: OPM insurgency (Indonesia), cross-border crime.
• Conservation: Lorentz NP (Indonesia) + PNG protected areas = largest tropical wilderness in Asia-Pacific.

Three islands, three binational (or trinational) management challenges.