Indonesia, Hercules maintenance, and the neutrality question

Indonesia is reportedly exploring opportunities to become a regional maintenance hub for C-130 Hercules aircraft. On paper, the proposal makes sense. Maintenance facilities promise technology transfer, industrial benefits, and stronger defence partnerships. For Indonesia, it also supports long-standing ambitions to strengthen domestic defence industry capabilities and expand its role within regional defence networks.

Under normal circumstances – peacetime – such arrangements attract little controversy. States routinely host maintenance facilities and sustainment arrangements for military equipment. But wartime often changes the strategic meaning of infrastructure built during peacetime.

Recent hostilities involving the United States and Iran offer a reminder of this reality. Modern conflicts rarely remain confined to immediate battlefields. Military operations increasingly spill into wider logistical systems and supporting infrastructure. States seeking to remain outside a conflict may nevertheless find themselves drawn into a broader operational picture.

The issue becomes more difficult in the context of a future US–China contingency.

A maintenance hub in a wartime environment

Indonesia may not become a participant in a US–China conflict. Yet geography means it could still sit within the wider operational picture in the Indo-Pacific.

Discussions surrounding a Taiwan contingency often focus on naval movements and maritime chokepoints. But modern military operations depend upon less visible infrastructure operating in the background.

A maintenance facility for military aircraft, therefore, has a strategic meaning during wartime.

From Washington’s perspective, sustainment arrangements improve operational reach and military endurance. But from Beijing’s perspective, infrastructure linked to US military logistics may be viewed differently. Facilities intended as technical cooperation can gradually acquire broader strategic significance.

Air neutrality was never quite like maritime neutrality

History suggests that neutrality law did not treat all forms of military movement equally.

On land, Hague Convention V adopted a restrictive approach. Neutral states could not allow troops or convoys to move through their territory. Trains carrying troops and war material were not simply regulated; they were excluded altogether.

At sea, however, the approach was different.

Hague Convention XIII recognised that naval operations depended upon access to ports. In practice, neutral ports historically functioned as limited spaces for naval sustainment, even if tightly regulated. Belligerent warships could enter neutral ports under restrictions. Their stay was limited and repairs were permitted only to the extent absolutely necessary to restore seaworthiness rather than increase fighting capability.

The experience of the German cruiser Admiral Graf Spee in neutral Uruguay during the Second World War reflected this logic. Following damage sustained in battle, the ship entered Montevideo and became subject to neutrality restrictions governing repair and duration of stay. Neutral access was restricted, but not prohibited outright.

Early efforts to regulate air warfare appear to have taken a different path.

The 1923 Hague Rules of Air Warfare provided that belligerent military aircraft were forbidden from entering neutral jurisdiction altogether. In that respect, aircraft appeared to be treated more like military transit on land than warships at sea.

The Hague Rules were never ratified. Yet later efforts appear to have retained much of the same logic. The HPCR Manual on International Law Applicable to Air and Missile Warfare generally maintained that belligerent military aircraft may not enter neutral airspace, subject to limited exceptions such as aircraft in distress, capitulation, and transit through international straits or archipelagic sea lanes. Even then, aircraft in distress entering neutral territory are expected to land and be interned until the war ends.

The broader pattern remains notable.

Examples of belligerent warships entering neutral ports and undergoing limited repairs are relatively easy to find. Military aircraft present a noticeably different pattern. Clear examples of belligerent military aircraft entering neutral territory, undergoing repairs, and returning to military operations appear remarkably difficult to identify. During the Second World War, military aircraft entering neutral territory were often interned rather than repaired and released for further military use.

Historically, neutral territory appears to have functioned as a limited sustainment space for naval operations. It is much less clear that it ever served a similar role for military air operations.

The next neutrality problem

For Indonesia, future neutrality pressures may not begin with requests for military bases or troop deployments.

They may begin with more ordinary forms of cooperation such as maintenance arrangements, logistics support, or technical infrastructure.

The law of neutrality was largely written around ports and railways. Today’s neutrality pressures may increasingly emerge through less visible infrastructure supporting military operations, such as military aircraft maintenance facilities, where the legal status remains uncertain and historical practice remains remarkably thin.