How far is Iran willing to go to protect its friends and allies?

Iran has been cultivating what it calls the Axis of Resistance for decades. It's a coalition of armed groups, backed by Tehran's money and often its weapons, that try to tip the scales of regional power in Iran's favour. Now the axis looks to be on shaky ground. Israel has marched into southern Lebanon, is pounding Beirut with bombs in an attempt to eliminate Hezbollah and says it doesn't plan to stop. So is Hezbollah the sticking point of ceasefire negotiations? And how far is Iran willing to go to back its friends and allies?