The waiting is over for those who pinned their hopes and fears for the next phase of the Syrian conflict on the outcome of the U.S. presidential election. But whatever approach is eventually adopted by the incoming administration of Donald Trump once it picks up the foreign policy reins in the early months of 2017, the fate of Aleppo will not wait. While the opposition perseveres in trying to lift the siege of the eastern part of the city, the arrival of Russian air and naval reinforcements in the Eastern Mediterranean and start of a bombing campaign by forces loyal to the regime of President Bashar al-Assad heralds a new military escalation.

But rather than seek to enable regime forces to fight their way into opposition-held neighborhoods, a more likely interpretation is that Russia hopes to avoid a drawn-out and costly battle by bludgeoning the opposition into agreeing to evacuate the city. This poses a major dilemma for the opposition: holding on in Aleppo remains feasible for it militarily, but the election of Trump, who has made clear his unwillingness to raise the stakes for Russia in Syria, means that the possible political rewards of holding on may diminish sharply. Conversely, the political costs of evacuating Aleppo may well outweigh any possible gains for the opposition.

The Israeli siege of the Lebanese capital Beirut in Summer 1982 offers a close analogy of the choices facing both besieger and besieged in Aleppo in 2016. Thirty-four years ago, Israel sought to break the back of Palestinian nationalism in the Israeli-occupied West Bank and Gaza by defeating the Palestine Liberation Organization (PLO), which was holed up in Beirut. Now, Russia wishes to break the back of the Syrian opposition generally, by defeating the armed groups in Aleppo. But Assad regime forces lack the numbers and morale to undertake the gruelling task of clearing dense urban neighbourhoods. And so like the Israel Defense Forces (IDF), who also did not wish to fight for Beirut street by street in 1982, Russia is using a mix of massed firepower, blockades of food, water, and electricity, and periodic offers of safe passage to civilians and fighters in order to coerce its adversary—in this case the Syrian armed opposition—to evacuate Aleppo unconditionally.

The military task lying ahead for the Syrian opposition is daunting, especially after UN humanitarian advisor Jan Egeland announced on November 18, 2016, that international food aid for the 275,000 people under siege in Aleppo had run out. But this only makes the political challenge facing the opposition even more acute. It may opt to prolong its resistance to the onslaught in the hope that international pressure on Russia will mount sufficiently, whether to bring about a lasting ceasefire and sustained humanitarian assistance or to extract substantial political gains in return for evacuating Aleppo. But how likely is effective international pressure to materialize, given the unmistakable retreat of regional backing for the Syrian opposition over the past year or more and the prospect of a sharp decline in U.S. engagement and support? More importantly still, would even the most favorable political gains the opposition might conceivably make in return for leaving Aleppo outweigh the material and symbolic costs of doing so?

The PLO faced a broadly similar dilemma in Beirut in 1982. It realized from the outset of the Israeli siege that it would have to evacuate the Lebanese capital, but decided to hold out for the best political terms it could obtain. However, the Arab states proved unwilling to sustain diplomacy on its behalf in the face of U.S. refusal to discuss anything other than the modalities of a PLO evacuation. Syria, the only Arab state to take part in the war, prioritized its own concerns: it quickly agreed a ceasefire with the IDF and subsequently blocked the transit of volunteers and arms to the PLO through its territory. And when France tabled a draft resolution at the UN Security Council calling for mutual PLO and Israeli withdrawals (as it did recently for Aleppo), the U.S. vetoed it (as did Russia recently). The U.S. later approved a joint French-Egyptian proposal linking the siege of Beirut to resolution of the Palestine problem, but almost immediately aborted it by proposing a competing diplomatic initiative of its own, which it then failed to pursue anyway.

Faced with diminishing diplomatic returns and escalating Israeli bombardment—including extensive use of air-burst and white phosphorous artillery shells, cluster munitions, and bunker-busting bombs against civilian apartment blocks suspected of harboring PLO leaders—and rapidly mounting civilian casualties—which formed 84 percent of the final death toll of the war—the PLO finally agreed to leave Beirut.

Despite enjoying significant material and diplomatic support from the U.S., leading members of the European Union, and key Gulf states over several years, the Syrian opposition is now in a position much closer to that of the PLO. Clearly, there are important differences. The opposition is fighting entirely on home ground, whereas the PLO faced calls from most of its own Lebanese allies to leave as soon as the IDF closed in on Beirut in 1982. Furthermore, while all PLO forces had left Lebanon by the end of 1983, opposition fighters pulling out of Aleppo would be able to regroup in adjacent parts of Syria, in the Aleppo countryside and in Idlib province.

But the consequences of evacuating Aleppo are likely to be far graver for the Syrian opposition than the departure from Lebanon ultimately was for the PLO. The latter redirected its effort into building the extensive grassroots movement that provided the backbone for the first intifada that erupted in the West Bank and Gaza Strip in 1987 and brought the PLO into direct dialogue with the U.S. administration the following year. But for the Syrian opposition, the loss of Aleppo would prompt external backers to curtail further support, while freeing regime troops and providing them with a springboard for operations against remaining opposition areas. Some rebels might abandon the struggle and go into exile, but others might join the jihadist camp or go underground to conduct a bombing campaign in regime areas, further eroding the opposition's domestic and international appeal.

Resolving the debate about what to do next may pose the toughest challenge for the Syrian opposition, especially for the groups inside Aleppo. The decision to leave Beirut in 1982 was reached unanimously by the PLO factions, but it still suffered a deeply debilitating internal rebellion and a six-month civil war that left some 400 dead the following year. It endured, but only by abandoning the military option and instead committing, gradually and painfully, to diplomacy. A decision to leave Aleppo may be even more divisive for the Syria opposition and could lead to internecine violence, as repeated episodes of infighting in besieged opposition enclaves—including Aleppo—in the course of 2016 have shown.

The stakes are high for the opposition in Aleppo, whose decision may determine the fate of the armed rebellion as a whole. Concern for the trapped civilian population may force its hand, but drawn-out sieges have been a hallmark of the Syrian conflict, and evacuation is not inevitable, or at least not imminent. Aleppo might instead go the way of other besieged locales such as the Yarmouk Palestinian refugee camp in Damascus or the four towns of Madaya, Zabadani, Foua, and Kefraya, which were covered by a cease-fire and evacuation agreement in September 2015, entering a state of suspended conflict.

But however long the Syrian opposition holds out in Aleppo, there is little prospect of its external backers coming to its aid; even less so with the election of Trump to the U.S. presidency. On the positive side, this may prompt Russia to lower the tempo of combat in Aleppo in the expectation that the Trump administration will not oppose it in Syria anyway, allowing it to reduce unnecessary costs and to focus on other operational objectives. But on the negative side, while the opposition can postpone the fate of the city, this underlines rather than resolves its continuing lack of a viable strategy to survive, let alone to win.

This article was originally published in Arabic in Al-Hayat.