Changing the rules of the game along Lebanon's southern border was the main challenge Hezbollah faced after the 2006 war with Israel. In the years since, the group has been touting deterrence as the main accomplishment of the war. Tit-for-tat strategies made the equation clear to all concerned, and both Israel and the Shiite Islamist group adhered to the de facto red lines. Since no one had any interest in igniting a new war, the Israeli-Lebanese border became the most stable area in a region prone to explosions. The Jan. 18 Israeli missile strike on the Golan Heights looks like it might alter the equation, although nothing in the immediate aftermath appears to have really changed.

The Israeli attack occurred outside Lebanese borders, but it represents the first major breach of the deterrence Hezbollah had established. The strike was something of a wake-up call to the Shiite organization, perhaps "distracted" by fighting in Syria for the past two years and advising allies in Iraq. The current situation leaves Hezbollah with few options, and all of them will leave a bitter taste.

One option is a strong response commensurate to the level of the Iranian and Lebanese commanders killed in the Israel attack. This, however, could lead to an Israeli reprisal and escalate tensions toward an unwanted, larger confrontation. Another option would be to remain calm for the time being and issue a public statement warning that Hezbollah reserves the right to retaliate at the appropriate time and location. This could be troubling to the popular base if not up to expectations while also sending the incorrect message to Israel that Hezbollah considers the era of mutual deterrence to have come to an end. Yet another, although unlikely, option, would be for Hezbollah to respond in a cold manner, conveying the message to the Israelis that no action they take will go without a response.

All three options are on the table, and Hezbollah is known to be deliberate when it comes to decisions such as the one it faces. Complicating the matter is that any considered response must involve two other parties: Iran, which lost a general from the Islamic Revolutionary Guard Corps (IRGC) in the Israeli strike and is considered the leader of the “resistance bloc,” and Syria, where the attack took place.