Providing weapons is a major intervention. That’s what the US did in the war between Pakistan and Bangladesh, and they ended up supporting a genocide.

You can try to rationalize a distinction by saying in that case, the US failed to support the people seeking independence. But then you have to be in the business of deciding which people’s claim of independence is legitimate. Supporting the jihadists in Afghanistan against the Soviet Union didn’t exactly end up well. Intervention is always rationalized in the moment.