The Iran-Syria nexus is a connection between the leadership of Iran and the Assad regime in Syria. This is a particularly important connection today as Assad’s regime faces a serious uprising against it that has led to a civil war in Syria. The major implication of the nexus is that the war might well continue for a long time and cause greater devastation in Syria.
Right now, Bashar Assad’s regime in Syria is in serious trouble. It is having a hard time fighting off rebels in the country and those rebels might be getting more help from the US and other Western countries in the near future. Therefore, the connection between Iran and Syria is very important for Syria. Iran wants to aid Assad because Syria is its closest ally in the region. Syria also has ties with Hezbollah, the militant group in Lebanon that is closely tied to Iran.
The connection between Iran and Syria means that the Assad regime continues to get help from Iran in fighting its civil war. This prolongs the war and causes greater suffering in the country.