What is Iran's 'Axis Of Resistance' against Israel?

Iran has systematically extended its influence in Middle East through a network of armed proxy groups, collectively called 'Axis of Resistance', which are now said to be preparing to respond to Israel over assassination of Hamas military chief Ismail Haniyeh. Hezbollah in Lebanon, Houthis in Yemen, Shi'ite militias in Iraq and Bashar al-Assad regime in Syria are part of it.