The West has only limited military options against IS in Syria-Iraq

BMI View: The US and its allies have only limited military options to fight Islamic State in Syria and Iraq, as there is no appetite for a large-scale deployment of ground troops. The most likely course of action is an intensified air campaign, featuring closer coordination with Russia. Even so, it will take many years to defeat IS.

Despite the severity of the November 13 Paris terrorist attacks, and the ongoing threat of Islamist militancy, the US and its allies are unlikely to commit to a large-scale ground offensive against Islamic State (IS)-controlled territory, as Western countries are war weary after long and inconclusive ground wars in Afghanistan (since 2001) and Iraq (2003-2011). This means that the likeliest Western response is an intensification of the air campaign against IS in Syria and Iraq.

Even If NATO Invokes Article 5, Large-Scale Ground Invasion Of Islamic State Unlikely

At this stage, it is unclear if NATO (as opposed to individual member states) will invoke Article 5, under which an attack on one member is considered an attack on all. Contrary to popular belief, Article 5 does not actually commit the alliance to military action. Rather, it states that "if such an armed attack occurs, each of [the member states], in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force [italics added], to restore and maintain the security of the North Atlantic area." But even if NATO responds against IS, a large-scale deployment of ground troops – by which we mean tens of thousands of soldiers – seems unlikely.

War Weariness In West Mitigates Against Ground Invasion

After long wars in Afghanistan and Iraq, Western countries are war weary, and wary of committing ground troops against IS. Ultimately, the US will determine the extent of the West's response. On this front, President Barack Obama on November 16 ruled out sending more ground troops (at present, the US has around 3,000 military advisers and trainers in Iraq and in late October said that it would send dozens of special forces to Syria). The US suffered around 4,500 troop deaths in Iraq and another 2,400 in Afghanistan, taking the total since 2001 to 6,900. While this is far fewer than the 58,000 who died in Vietnam during the 1960s-1970s, the US public's tolerance for casualties is believed to be far lower nowadays than in previous decades. Other Western countries have lost hundreds of troops in Afghanistan and Iraq since the early 2000s. There is also the huge financial cost of the Afghan and Iraqi wars. This has been estimated at USD2.7trn.

Ground Troop 'Surges' In Iraq And Afghanistan Could Not Decisively Defeat Insurgencies

Yet, even if the US and its allies were to send in tens of thousands or even 100,000-200,000 troops into Syria and Iraq, there is no guarantee that they would succeed in defeating IS. Although the Afghan Taliban and regime of Saddam Hussein were quickly ejected from power following US-led invasions in 2001 and 2003, respectively, long insurgencies followed in both countries. A US troop 'surge' in Iraq in 2007, taking the American total to from 140,000 to 170,000, temporarily mitigated the insurgency, but this also required the co-optation of some Sunni militant groups to fight against others. Once US troops left Iraq in December 2011, the country became unstable once again, ultimately paving the way for the rise of IS. In Afghanistan, a similar 'surge' in 2010 took the NATO-led coalition's troop total to almost 150,000, and this was backed by more than 200,000 Afghan National Army troops. Even so, this was not enough to defeat the Taliban, which remains very active.

Afghanistan and Iraq both have populations greater than 30 million, whereas the territory controlled by Islamic State contains only around eight million people. This implies that far fewer troops than those committed to Afghanistan and Iraq would be necessary to invade and occupy the statelet. Yet even if Islamic State were abolished as a geographical entity, we would expect the organisation to stage an insurgency against Western troops, and more terrorist attacks against the West.

We deem it more likely that Western countries will send small numbers of special forces to work with organisations in Syria and Iraq fighting against IS.

Air Campaign To Be Greatly Expanded

We also expect the US and its allies to greatly expand their air campaign against IS, which began against Iraq in August 2014, and against Syria the following month. According to the US Department of Defense, as of November 12, 2015, the Coalition had carried out 8,125 strikes against IS, of which 5,321 were in Iraq and 2,804 in Syria. Of these, the US had conducted 6,353 strikes (78%), of which 3,695 were in Iraq and 2,658 in Syria. Other countries that have participated in strikes in Iraq are Australia, Belgium, Canada, Denmark, France, Jordan, the Netherlands, and the UK, while countries that have struck IS in Syria are Australia, Bahrain, Canada, France, Jordan, Saudi Arabia, Turkey, and the United Arab Emirates. For its part, Russia's General Staff stated on November 17 that it had carried out 2,300 sorties against targets in Syria since the start of air operations on September 30.

The intensity of the air campaign against IS appears to be low by post-Cold War standards. For example, over a 78-day period from March to June 1999, NATO carried out 10,484 strike sorties against the Federal Republic of Yugoslavia (i.e. Serbia and Montenegro) to defend Kosovo Albanians from a Serbian crackdown. This involved more than 1,000 NATO aircraft flying over Serbia at the height of the campaign. In addition, the US-led multinational coalition conducted more than 100,000 sorties (including non-strike sorties) against Iraq over six weeks in the Gulf War of 1991. Although it is difficult to make like-for-like comparisons between present and previous air campaigns, it appears that the offensive against IS has been much less intense than previous Gulf and Balkan air wars. This implies that there is considerable scope for intensification – although this would also bring a greater risk of civilian casualties, thus increasing local anger towards the West.

Greater De Facto Western Cooperation With Russia Likely

France is already moving towards closer military co-operation with Russia against IS. Western countries have criticised Russia's airstrikes for mainly targeting non-IS organisations that are often labelled 'moderate' rebels, even though their ultimate intentions are unclear. Now, however, we see scope for more de facto coordination between Russia and the West against IS. Given that Iran has deployed military forces against IS, there is also scope for international coordination with Tehran.

Assad's Removal Less Of A Priority For West, At Least For Now

The rise of IS since 2014 has led to a reassessment in the West of the urgency to remove Syrian President Bashar al-Assad. Top political leaders still generally advocate his exit, on the grounds that his forces' brutality in 2011-2013 paved the way for the emergence of IS, and that Assad has been more interested in fighting 'moderate' rebels than IS. However, it is also true that Assad's regime is still the strongest single force in Syria, and the nearest thing to a functioning government, controlling 60% of the population and the country's core economic areas. In that sense, Western leaders have stated in recent months that Assad could remain in office for a 'transitional' period. Given that such a 'transition' could last several years, this suggests that Western countries may find themselves in de facto cooperation with the regime. While we believe that the West still favours Assad's departure, this no longer seems an immediate priority.

US's Middle Eastern Allies Still Reluctant To Commit In Full Force

Middle Eastern allies of the West, such as Turkey and Saudi Arabia, have been reluctant to commit to the war against IS. Ankara has been more interested in suppressing Kurdish separatism in Iraq and Syria, while Riyadh has prioritised fighting Houthi rebels in Yemen as part of a wider regional power-play against Iran. Turkey may adopt a more hawkish stance towards IS under Western pressure and because of an IS attack in Ankara on October 10, but even so, President Recep Tayyip Erdogan appears to be more interested in removing Syrian President Bashar al-Assad than defeating IS.

West Needs To Encourage Divisions Within IS

Islamic State is far from a truly united movement, and there have been several reports of considerable internal divisions over ideology, doctrine, and whether to consolidate its home territory or 'go global'. There have also reportedly been tensions between local Syrian and Iraqi fighters, and foreigners who have joined their ranks, over issues such as pay. In addition, IS has already publicly fallen out with al-Qaeda. Given these factors, Western and allied intelligence agencies need to find ways to encourage rifts within the IS movement – although this will be easier said than done. Disrupting IS's economic and financial lifelines will also become more urgent.

Next US President To Adopt Tougher Approach, But Options Will Still Be Limited

A more decisive effort by the US to fight IS will probably not emerge until after the November 2016 presidential election. Ultimately, the West's fight against IS will be determined by what the US does, since it remains the single most powerful actor in the world. However, President Barack Obama has only 14 months left in office, which is insufficient to bring about a decisive US response. In addition, the US political establishment will be reluctant to see the start of a major military campaign in the Middle East, due to the unpredictable impact that this would have on the 2016 election campaign.

Even so, terrorism and security issues are likely to rise up the agenda in the US political debate, and we maintain our view that regardless of whether the next US president is a Democrat or Republican, we will see a more assertive foreign policy posture from January 2017. Democratic party frontrunner Hillary Clinton has much more interventionist leanings than Obama, and Republicans have traditionally favoured a robust global military profile. That said, even a more hawkish occupant of the White House would still face the constraints we described above. One wild card would be an IS-instigated mass-casualty terror attack in the United States itself. This could force Washington's hand in a ground invasion.