Why is Rafah so Important?

US President Joe Biden has warned Israel against launching a major attack on Rafah, saying he would withhold certain weapons that could be fired into the densely populated region. Earlier, Biden also said he would block the delivery of artillery shells. The US had already stopped a shipment of 3,500 bombs before this. Israel is fuming over Biden’s announcement amid concerns of straining its relationship with the US. Why is Rafah so important? News9 Plus decodes.