The current main concerns along the fortified Blue Line separating Israel and Lebanon are whether a war with Hezbollah is imminent, and if so how it might be averted. The discovery of three attack tunnels dug by Hezbollah and intruding into Israeli territory has dangerously narrowed the margin of error for both sides. The construction of these tunnels — and there may be more — in flagrant violation of Israel’s sovereignty and of UN Security Council resolutions is a provocation that Hezbollah are going to find hard to justify. It makes the threats by its leader, Hassan Nasrallah, about his organization’s intention “to conquer the Galilee” in the next war more credible, which is something Israel cannot afford to take lightly. As in most issues involving Israel and Hezbollah, there are a number of plots and subplots. As much as it is an ongoing conflict between two sides that have been sworn enemies since Israel’s ill-conceived invasion of Lebanon in 1982, it is also to a large extent a proxy war between Israel and Iran that serves the domestic interests of both governments. It may be that memories of the bloody consequences of a real war are not as vivid as they should be. Therefore it is worth recalling that during the last round of hostilities neither side came out on top; both suffered substantial loses and they have been licking their wounds ever since. Another flare-up is likely to be even more costly. Regional powers and the international community must be on high alert and warn the protagonists against letting the situation escalate into a limited, or even a full-blown, conflict. The cynics would argue, with some justification, that the unearthing of the tunnels and the operation to destroy them was too politically and personally convenient for Israeli Prime Minister Benjamin Netanyahu to be mere coincidence. Diverting public attention while he is up to his neck in corruption investigations — and as police recommend he be indicted, along with his wife and others close to him — is blissful respite from his domestic problems. Putting cynicism and considerations of individual political survival aside, however, to have discovered and destroyed the tunnels before they could become fully operational is an important achievement for Israel. It has saved Hezbollah, and with it Lebanon, from its temptation and folly. After all, it is not within that organization’s military capabilities to “conquer the Galilee.” Nevertheless, that it might have been able to send its Radwan commando unit into Israeli territory undetected through the tunnels posed a real threat. It would have given Hezbollah the crucial element of surprise and enabled it to take control of Israeli territory, if only for a short time, and probably terrify the local population. For the Jewish state this is a nightmare scenario, as it would probably result in many casualties, both military and civilian. It would require a mass evacuation from areas along its northern border, not to mention confronting enemy forces on its own territory, which is not something the Israel Defense Forces are comfortable with. They would rather operate beyond their own borders than confront guerrillas inside Israel. The discovery of three attack tunnels dug by Hezbollah and intruding into Israeli territory has dangerously narrowed the margin of error for both sides. Yossi Mekelberg Moreover, should Nasrallah’s forces ever manage to execute such a plan it would probably force Israel to retaliate with massive force to re-establish calm along its northern border and act as a long-term deterrent — a response that might result in even worse destruction and bloodshed than in the summer of 2016. Add to this that any military achievement for Hezbollah is one for Tehran too, and the volatility of the Blue Line becomes explosive. Nasrallah, who has been on the run and in hiding for the past 12 years, views Israel as a useful enemy. Confronting it is part of his domestic calculus, and the best way to maintain political, financial and military support from Iran. With the war in Syria approaching some kind of conclusion, Hezbollah fighters are returning home to Lebanon, having acquired significant battlefield experience that they will find useful in future confrontations. However, they have also sustained heavy casualties, and the organization and its leaders have been criticized for getting embroiled in a war that did not serve the interests of Lebanon. Despite doing well in last May’s elections, Hezbollah are treated with great suspicion in many political quarters, and there is a fear that should they become entangled in another war with Israel, they will not be the only ones to pay the price for it. Hezbollah’s acquisition of up to 150,000 short-to-long-range rockets and missiles — which put the entire state of Israel within range— has been keeping both sides on edge for more than a decade. Its recently exposed tunneling into Israeli territory shows how dangerous the situation has become. Any wrong move, politically or militarily, could end in calamity for both sides. On this occasion it is not only Nasrallah who must come up with some explanations, but also Tehran, which is playing its own part in heating up tensions along the Blue Line. Yossi Mekelberg is professor of international relations at Regent’s University London, where he is head of the International Relations and Social Sciences Program. He is also an associate fellow of the MENA Program at Chatham House. He is a regular contributor to the international written and electronic media. Twitter: @YMekelberg Disclaimer: Views expressed by writers in this section are their own and do not necessarily reflect Arab News" point-of-view