What does the term "expeditionary warfare" refer to?

Expeditionary warfare specifically refers to military operations that involve deploying forces to and conducting operations in hostile territory, often with the purpose of achieving a strategic objective. This type of warfare typically includes the establishment of a foothold in the area, allowing for follow-on forces and logistical support to enter and sustain operations.

In the context of the correct answer, "operations that involve landing forces on hostile territory" encapsulates the core aspect of expeditionary warfare, which is the need to project military power onto land where enemy forces or threats are present. This can include a variety of missions such as amphibious assaults, counterinsurgencies, or stabilization efforts, but the fundamental concept remains centered around engaging and establishing a presence in enemy-controlled areas.

The other options do not accurately encompass the full scope of expeditionary warfare. For example, support operations for maritime patrol primarily involve surveillance and defense at sea rather than ground engagements. Ground operations in friendly territory imply an absence of hostilities and are more aligned with peacekeeping or support roles, which is fundamentally different from the offensive nature of expeditionary warfare. Similarly, naval engagements with air support focus on naval combat operations rather than involving land forces operating in hostile environments.