How Do We Classify Conflict?

After WWII, it became common for third party states to intervene in civil wars on behalf of a government or to support rebel groups, making distinct conflict classification more difficult.

Such can be observed through the example of Russian-Syrian relations amidst the Syrian civil war: though Russia continues to support Syrian armed forces at the request of President Asad in his fight against several rebel groups, the conflict is still considered to be of non-international nature.

Does foreign intervention change the nature of conflict?

Where a state intervenes in support of a government's battle against a rebellion in a given country, the conflict remains non-international. However, where a third intervening state supports the rebels, against a territorial government (e.g. the United States in Nicaragua) the conflict has potential to be international.

For this to actually occur, the intervening state must possess 'effective control' over the rebel group and communicate to the rebel group with clear instructions etc.

This 'effective control' as a deciding factor is widely debated: the International Criminal Tribunal for the Former Yugoslavia in the 1999 Tadić Appeals Judgement ruled 'overall control' (which is less demanding than effective control) when they assessed whether the Bosnian-Herzegovinian Conflicts had changed in consequence to Serbian influence on the Bosnian Serbs. It was ruled that 'overall control' was fulfilled due to the Serbian government's actions of providing financial and operational support to Bosnian Serbs, and helping with their coordination and general planning of military activities. Thus, it was declared an international armed conflict, no longer a non-international armed conflict, between Serbia and Bosnia-Herzegovina.

NIAC spill-overs (into a neighbouring country)

Allow for contemplation of the following hypothetical:

A civil war occurs between rebels and the government in given country 'A', and a group of the rebels take refuge in neighbouring country 'B'. If the country 'A' wants to send their troops to attack the rebels in country 'B' could this NIAC can be considered international?

(1) If country 'B' consents to country 'A's troops on their territory (supporting country 'A') the conflict would stay classified as non-international since it is not a conflict between two states.

however

(2) If country 'B' does not consent (not supporting country 'A') it can turn into an international conflict, even if the only party attacked by country 'A' is the rebel group, not country 'B' itself.

Situations that fall below thresholds of armed conflict

According to Common Article 3 of the Geneva Conventions, situations not covered by the legislations of IHL are instead governed by domestic law enforcement, domestic legal regimes and human rights laws. Article 1, paragraph 2 of Additional Protocol II supports this idea.

Sporadic acts of violence are not covered by IHL either, such as spontaneous terrorist acts.