Relations between the Bashar al-Assad regime in Damascus and the Lebanese Resistance had already reached a high-level of coordination and mutual support even before the outbreak of the Syrian crisis. At the time, the two allies tended to respect each others’ boundaries, recognizing each other’s key roles in the region.
The onset of the Syrian crisis only served to further intertwine their interests as both became targets of the Syrian opposition and their regional and international backers.
In the early stages of the uprising, Hezbollah tried to play the role of mediator, seeking ways to open up channels between the regime and the opposition. But quickly, developments – like Israel’s growing involvement in the crisis – prompted a qualitative change in the relationship between Damascus and the Lebanese Resistance.
Assad’s response to the latest Israeli attacks on Damascus would have not meant much if it did not also have the strong support of Hezbollah, Iran, and even Russia – with the Resistance openly declaring its willingness to take part in any effort to ward off Tel Aviv’s threats.
http://english.al-akhbar.com/content/hezbollah-intervention-syria-redraws-political-map