Israel's defense establishment closed out 5774 with a smile. The downing of a Syrian fighter plane, the killing of the terrorists who kidnapped and murdered the three teens and the reception of the INS Tanin submarine marked a good end to a tough year, and also represented a clear indication of what we can expect in the coming year. The main challenge in 5775 will be in the north. The Syrian side of the Golan Heights has slowly fallen into the hands of the rebels, who are currently focused on fighting the Assad regime forces that still remain in a number of villages in the area. Even without solid information on whether or not the downed Sukhoi Su-24 fighter plane was taking part in this fighting, the Israeli Air Force had no choice but to shoot it down from the moment it crossed the border. An IAF official rightly compared the scenario to one in which a terrorist crosses the border fence on the ground. In both cases, Israel's defense must be hermetic. Once the identity of the infiltrator is known, there is no time for further questions. Any deviation from this would put the lives of Israeli civilians at risk and be dangerously perceived on the other side on the border as hesitancy on Israel's part. For the moment, at least, Syrian President Bashar Assad has no interest in fighting Israel. The immediate threat to his regime is from within -- in the form of the rebel groups, led by the Islamic State and the Nusra Front. Opening fire at Israel would turn Assad back into the villain in the story exactly at a time in which the world is coming to his aid (albeit not openly) by means of the Western-Arab military campaign against the Islamic State, a campaign that expanded from Iraq into Syria on Tuesday. Nevertheless, Israel's northern border remains volatile. The fighting in Syria often spills over the border, which could lead to a localized flare-up. Jihadist groups in Syria are quickly taking over land and seizing new weaponry, and they could decide to act against Israel. Also, Hezbollah is displaying increasing signs of nervousness, in light of the attacks it has faced in Lebanon as well as alleged Israeli strikes on its assets in recent years. There is concern that the deterrence Israel established during the Second Lebanon War, which led to eight years of quiet in the north, is slowly but surely eroding away. The increasing sensitivity in the north stands in stark contrast to the relative calm vis-a-vis the Palestinians. The Israel Defense Forces and the Shin Bet believe that Hamas and other terrorist groups in the Gaza Strip have no interest in attacking Israel in the near future. The pullout of the Palestinian delegation from the Cairo talks on Tuesday due to the killing of the teens' murderers was short-lived. There could, however, be localized riots in Hebron and attempts to avenge the deaths, which is why the IDF has bolstered its presence in the area and is coordinating with the Palestinian Authority security forces. The killing of Marwan Qawasmeh and Amer Abu Aisheh on Tuesday was an intelligence achievement. But while the Shin Bet must be credited for finding the killers, it must also be faulted for not thwarting their attack in the first place. The Shin Bet has to learn lessons from this episode, so it can prevent the next attack, which is certainly already in the works. Yet, it is unlikely that "quality terrorist attacks" will be the story of the coming year. Rather, it is believed the main headache, which is expected to get worse, will be "popular terrorist attacks" (i.e., stones and firebombs), particularly in east Jerusalem. The challenging budgetary reality means the defense establishment will have to stretch itself to find an answer to this threat, knowing that a failure -- like the events that happened this past summer -- could initiate a dangerous process. A local event, like the kidnapping and murder of the three teens, could lead to wider fighting or even a multi-front conflict.