Why arms supply differs from direct intervention

Why could states arm Ukraine while avoiding direct military protection?

Supplying weapons could remain legally and diplomatically distinct from openly deploying forces to fight, although the boundary depended on treaties and perception.

The main line lies between direct participation in combat and the supply of weapons to a belligerent. Sending ships or troops to fight openly would be treated as an act of war. Arms transfers occupy a different position when no United Nations embargo or other binding prohibition blocks them. Treaty wording, sanctions, and political perception still create grey areas even when the transfer is technically permitted. This is a March 2022 diplomatic and legal framing rather than a complete legal ruling on every form of assistance.