Islamic State (Isis) will remain at the centre of the escalating crisis in the Middle East this year as it was in 2014. The territories it conquered in a series of lightning campaigns last summer remain almost entirely under its control, even though it has lost some towns to the Kurds and Shia militias in recent weeks.

United States air strikes in Iraq from 8 August and Syria from 23 September may have slowed up Isis advances and inflicted heavy casualties on its forces in the Syrian Kurdish town of Kobani. But Isis has its own state machinery and is conscripting tens of thousands of fighters to replace casualties, enabling it to fight on multiple fronts from Jalawla on Iraq's border with Iran to the outskirts of Aleppo in Syria.

In western Syria, Isis is a growing power as the Syrian government of President Bashar al-Assad loses its advantage of fighting a fragmented opposition, that is now uniting under the leadership of Isis and Jabhat al-Nusra, the Syrian affiliate of al-Qaeda.

Yet it is only a year ago that President Obama dismissed the importance of Isis, comparing it to a junior university basketball team. Speaking of Isis last January, he said that "the analogy we use around here sometimes, and I think it is accurate, is if a JV [junior varsity] team puts on Lakers uniforms it doesn't make them Kobe Bryant [famed player for the Los Angeles Lakers basketball team]." A year later Obama's flip tone and disastrously inaccurate judgement jumps out at one from the page, but at the time it must have been the majority view of his national security staff.

Timeline: The emergence of Isis Show all 40 1 /40 Timeline: The emergence of Isis Timeline: The emergence of Isis 2000 Abu Musab al-Zarqawi (pictured here) forms an al-Qaeda splinter group in Iraq, al-Qa’eda in Iraq. Its brutality from the beginning alienates Iraqis and many al-Qaeda leaders. Timeline: The emergence of Isis 2006 Al-Zarqawi is killed in a U.S. strike. Al-Zarqawi’s successor, Abu Ayyub al-Masri, announces the creation of the Islamic State in Iraq (ISI). Reuters Timeline: The emergence of Isis 2009 Still al-Qaeda-linked ISI claims responsibility for suicide bombings that killed 155 in Baghdad, as well as attacks in August and October killing 240, as President Obama announces troop withdrawal from Iraq in March. Getty Images Timeline: The emergence of Isis 2010 Abu Bakr al-Baghdadi becomes head of ISI, at lowest ebb of Islamist militancy in Iraq, which sees last U.S. combat brigade depart. Timeline: The emergence of Isis 2012 In Syria, protests (pictured here starting in Daree) have morphed into what president Assad labelled a “real war” with emergence of a coalition of forces opposed to Assad’s regime. Syria group Jabhat al-Nusra are among rebel groups who refuse to join, denouncing it as a “conspiracy”. Bombings targeting Shia areas, killing more than 500 people, spark fears of new sectarian conflict. Sunni Muslims stage protests across country against what they see as increasingly marginalisation by Shia-led government. AP Timeline: The emergence of Isis 2013 Al-Baghdadi renames ISI as the Islamic State in Iraq and Syria, or Isis, as the group absorbs Syrian al-Nusra, gaining a foothold in Syria. In response, al-Qaeda chief Ayman al-Zawahiri (Bin Laden’s successor) concerned about Isis’ expansion orders that Isis be dissolved and ISI operations should be confined to Iraq. This order is rejected by al-Baghdadi. AFP Timeline: The emergence of Isis 2014 - January Isis fighters capture the Iraqi cities of Fallujah and Ramadi, giving them base to launch slew of attacks further south. AP Timeline: The emergence of Isis 2014 - June Isis declares itself the Caliphate, calling itself Islamic State (IS). The group captures Mosul, Iraq’s second largest city; Tal Afar, just 93 miles from Syrian border; and the central Iraqi city of Tikrit. These advances sent shockwaves around the world. Timeline: The emergence of Isis 2014 - June Around the same time Isis releases a video calling for western Muslims to join the Caliphate and fight, prompting new evaluations of extremists groups social media understanding. Timeline: The emergence of Isis 2014 - June Isis take Baiji oil fields in Iraq - giving them access to huge amounts of possible revenue. EPA Timeline: The emergence of Isis 2014 - August James Foley is executed by the group as concerns grow for second American prisoner, fellow reporter Steven Sotloff. AP Timeline: The emergence of Isis 2014 - August Obama authorises U.S. airstrikes in Iraq, helping to stall Isis’ along with action by Kurdish forces following the deaths of hundreds of Yazidi people on Mount Sinjar. Timeline: The emergence of Isis 2014 - September Isis release video showing Steven Sotloff’s murder prompting Western speculation his executioner is same man who killed Mr Foley. EPA Timeline: The emergence of Isis 2014 - September Obama tells us that America “will hunt down terrorists who threaten our country” EPA Timeline: The emergence of Isis 2014 - September Isis release a video appearing to show David Haines, who was captured by militants in Syria in 2013, wearing an orange jumpsuit and kneeling in the desert while he reads a pre-prepared script. It later shows what appears to be the aid worker's body. Rex Timeline: The emergence of Isis 2014 - September Peshmerga fighters scrabble to hold positions in the Diyala province (a gateway to Baghdad) as Isis fighters continue to advance on Iraqi capital. AFP Timeline: The emergence of Isis 2014 - October Aid worker Alan Henning is killed. Self-imposed media blackout refuses to show images of him in final moments, instead focuses upon humanitarian care. AP Timeline: The emergence of Isis 2014 - October Isis raise their flag in Kobani, which had been strongly defended by Kurdish troops. The victory goes against hopeful western analysis Isis had overextended itself, while alienating much of the Muslim population through the murder of Henning. Victory causes fresh waves of Kurdish refugees arriving in Turkey. Timeline: The emergence of Isis 2014 - November American hostage, who embarced values of Islam, Peter Kassig and 14 Syrian soldiers are shown meeting the same fate as other captives. But intelligence agencies will be poring over the apparently significant discrepancies between this and previous films. Seramedig.org.uk Timeline: The emergence of Isis 2015 - February Isis has released a video revealing the murder by burning to death of a Jordanian pilot held by the group since the end of December 2014. Reuters Timeline: The emergence of Isis 2015 - February Isis militants have released videos which appear to show the beheading of Japanese hostages Haruna Yukawa and Kenji Goto. Timeline: The emergence of Isis 2015 - February American aid worker, Kayla Mueller was the last American hostage known to be held by Isis. She died, according to her captors, in an airstrike by the Jordanian air force on the city of Raqqa in Syria, though US authorities disputed this. AP Timeline: The emergence of Isis 2015 - February Isis militants have posted a gruesome video online in which they force 21 Egyptian Coptic Christian hostages to kneel on a beach in Libya before beheading them. Egypt vowed to avenge the beheading and launched air strikes on Isis positions. AP Timeline: The emergence of Isis 2015 - February The British Isis militant suspected of appearing in videos showing the beheading of Western hostages has been named in reports as Mohammed Emwazi from London. Rex Features Timeline: The emergence of Isis 2015 - March Isis triple suicide attack has killed more than 100 worshippers and hundreds of others were injured after the group members targeted two mosques in the Yemeni capital of Sanaa. AP Timeline: The emergence of Isis 2015 - April Iraqi forces have claimed victory over Isis in battle for Tikrit and raised the flag in the city. EPA/STR Timeline: The emergence of Isis 2015 - April Isis has claimed responsibility for a suicide bomb attack in Afghanistan that killed at least 35 people queuing to collect their wages and injured 100 more. EPA Timeline: The emergence of Isis 2015 - April Isis’ media arm released a 29-minute video purporting to show militants executing Ethiopian Christians captives. The footage bore the extremist group’s al-Furqan media logo and showed the destruction of churches and desecration of religious symbols. A masked fighter made a statement threatening Christians who did not convert to Islam or pay a special tax. Timeline: The emergence of Isis 2015 - May Abu Bakr al-Baghdadi, the leader of Isis has been "incapacitated" by a spinal injuries sustained in a US air strike in Iraq. He is being treated in a hideout by two doctors from Isis’ stronghold of Mosul who are said to be "strong ideological supporters of the group". Timeline: The emergence of Isis 2015 - May Isis has also claimed responsibility for killing 300 of Yazidi captives, including women, children and elderly people in Iraq AP Timeline: The emergence of Isis 2015 - May Isis attack on Prophet Mohamed cartoon contest in Texas was its first action on US soil. Two gunmen were shot and killed after launching the attack at the exhibition. Elton Simpson and Nadir Soofi have been named as the attackers at the Curtis Culwell Centre arena in Garland. Timeline: The emergence of Isis 2015 - May Isis’s deputy leader, Abu Alaa Afri, a former physics teacher who was thought to have taken charge of the deadly terrorist group, has been killed in a US-led coalition airstrike. Timeline: The emergence of Isis 2015 - May US special forces have killed a senior Isis leader named as Abu Sayyaf in an operation aiming to capture him and his wife in Syria. Getty Images Timeline: The emergence of Isis 2015 - May Iran-backed militias are sent to Ramadi by the Iraqi government to fight Isis militants who completed their capture of the city. Government soldiers and civilians were reportedly massacred by extremists as they took control and the army fled. Charred bodies were left littering the city streets as troops clung on to trucks speeding away from the city. Ramadi is the latest government stronghold to fall to the so-called Islamic State, despite air strikes by a US-led international coalition aiming to stop its advance in Iraq and Syria. AFP Timeline: The emergence of Isis 2015 - May Isis rounded up civilians trapped in Palmyra and forced them to watch 20 people being executed in the historic city’s ancient amphitheatre. The Unesco World Heritage site was overrun by militants, threatening the future of 2,000 year-old monuments and ruins. Thousands of Palmyra’s residents fled but many are still living within the city walls, while the UN human rights office in Geneva said it had received reports of Syrian government forces preventing people from leaving until they retreated from the city. Getty Timeline: The emergence of Isis 2015 - May A group of Isis-affiliated fighters have captured a key airport in central Libya. The militants took control of the al-Qardabiya airbase in Sirte after a local militia tasked with defending the facility withdrew from their positions. Affiliates of Isis, already control large parts of Sirte, the birthplace of former Libyan leader Muammar Gaddafi and a former stronghold of his supporters. Timeline: The emergence of Isis 2015 - June The US Air Force has destroyed an Isis stronghold after an extremist let slip their location on social media. According the Air Force Times, General Herbert "Hawk" Carlisle, commander of Air Combat Command, said that Airmen at Hulburt Field, Florida, used images shared by jihadists to track the location of their headquarters before destroying it in an airstrike. Reuters Timeline: The emergence of Isis 2015 - June Kurdish forces captured a key military base in a significant victory in Raqqa as well as town of Tell Abyad. YPG fighters, backed by US-led airstrikes and other rebels, consolidated their gains, when they seized the key town on the Syria-Turkey border. They are now just 30 miles to the north of Raqqa and have cut off a major supply route deep inside Isis-held territory. Ahmet Silk/Getty Timeline: The emergence of Isis 2015 - June Isis has released gruesome footage claiming to show the murder of more than a dozen men by drowning, decapitation and using a rocket-propelled grenade as it seeks to boost morale among its fanatical supporters. Timeline: The emergence of Isis 2015 - June Isis has begun carrying out its threat to destroy structures in the ancient Syrian city of Palmyra, blowing up at least two monuments at the Unesco-protected site as Syrian government troops made advances on the Islamist’s positions. AFP

Underrating the strength of Isis was the third of three great mistakes made by the US and its Western allies in Syria since 2011, errors that fostered the explosive growth of Isis. Between 2011 and 2013 they were convinced that Assad would fall in much the same way as Muammar Gaddafi had in Libya.

Despite repeated warnings from the Iraqi government, Washington never took on board that the continuing war in Syria would upset the balance of forces in Iraq and lead to a resumption of the civil war there. Instead they blamed everything that was going wrong in Iraq on Prime Minister Nouri al-Maliki, who has a great deal to answer for but was not the root cause of Iraq's return to war. The Sunni monarchies of the Gulf were probably not so naïve and could see that aiding jihadi rebels in Syria would spill over and weaken the Shia government in Iraq.

How far has the political and military situation changed today? Isis has many more enemies, but they remain divided. American political and military strategies point in different directions. US air strikes are only really decisive when they take place in close cooperation with troops on the ground. This happened at Kobani from mid-October when the White House decided at the last minute that it could not allow Isis to humiliate it by winning another victory. Suddenly the Syrian Kurdish fighters battling IS shifted from being "terrorists" held at arm's length to being endangered allies. As in Afghanistan in 2001 and in northern Iraq in 2003, experienced personnel in the front line capable of directing the attacks of aircraft overhead are essential if those strikes are to be effective.

When the bombing of IS in Syria started, the government in Damascus felt that this was to its advantage. But while the US, Arab monarchies, Syrian rebels and Turkey may have overplayed their hands in Syria between 2011 and 2013, last year it was the Syrian government that did the same thing by seeking a solely military solution to the war. It has never seriously tried to broaden its political base at home by credible offers to share power, relying instead on its supporters to go on fighting because they believe that anything is better than a jihadi victory. But these supporters are becoming worn out by the struggle because they see no end in sight.

The government has always been short of combat troops, a weakness becoming more apparent as it calls up more reservists and diverts conscripts from entering the National Defence Force militia into the regular army. Government forces have made gains around Aleppo and Damascus, but they are losing ground south of the capital and in Idlib province.

There have always been political advantages for Assad at home and abroad in having the Syrian rebels dominated by "terrorists" of whom the West is frightened. But the dominance of Isis and Jabhat al-Nusra means that the Syrian army is losing its advantage of being a single force facing a disunited foe with 1,200 different factions. A sign of this underlying weakness is the failure of government troops to launch an expected offensive to retake rebel held parts of Aleppo.

Isis won great victories in Iraq in the course of the year by taking advantage of the alienation of the Iraqi Sunni Arab community. This tied the Sunnis' fortunes to Isis and, while they may regret the bargain, they probably have no alternative but to stick with it.

The war has become a sectarian bloodbath. Where Iraqi army, Shia militia or Kurdish peshmerga have driven Isis fighters out of Sunni villages and towns from which civilians have not already fled, any remaining Sunni have been expelled, killed or detained. Could Isis launch another surprise attack as in June? This would be difficult outside Sunni-majority areas, though it could provoke an uprising in the Sunni enclaves in Baghdad, probably with disastrous results for the remaining Sunni in the capital. They were forced out of mixed areas in 2006 and 2007 and mostly confined to what a US diplomatic cable at the time called "islands of fear" in west Baghdad. Isis could create mayhem in the capital, but the strength of the Shia militias is such that it would probably be at the price of the elimination of remaining Sunni enclaves.

Syria's two main foreign backers, Russia and Iran, are both suffering from the collapse in the oil price. This may make them more open to a power-sharing compromise in Syria, but it is by no means clear that they are being offered a deal by the West and its Arab allies. This may be a mistake since at the end of the day the great confrontation between Sunni and Shia across the Muslim world is not going to be decided by Iranian or Russian budgetary problems. Iraqi Shia militia units that withdrew from Syria to fight Isis in Iraq can always be sent back and reinforced.

The Iranians really do feel this is a war they cannot lose whatever the impact of economic sanctions imposed by the US. The balance of power between government and Isis looks fairly even in Iraq at the moment, but this is not true in Syria where Sunni Arabs are 60 per cent of the population as opposed to 20 per cent in Iraq. Above all, Isis is strengthened in Syria by the fact that the West, Turkey and the Sunni Arab states are seeking the fall of Assad, Isis's main opponent, as well as the overthrow of Isis itself.