Various Israeli assessments say that the organization that calls itself the Islamic State of Iraq and the Levant — Islamic State for short — has lost more than one-third of its fighting members over the past 18 months. Israeli and other Western officials estimated the number of its combat fighters at roughly 25,000 in early 2015. The current estimate stands at approximately 15,000.

The decline has several causes. The first is the joint American-Russian military effort against Islamic State in some sectors — an effort that has claimed many casualties and an enormous number of wounded. Meanwhile, it has exhausted itself battling the Syrian army, Hezbollah, Shiite militias, Turkey, the Kurds, the Arab coalition, and the Syrian opposition.

The flow of volunteers has all but stopped. This, too, seems to be linked to several factors, such as Turkey’s military intervention on Syrian territory last month, which has made it difficult for volunteers to get through; the first battlefield defeats in major cities such as Fallujah, Ramadi, Minbaj, and Palmyra, which hurt Islamic State’s image as an undefeated power; and more strenuous efforts by European countries against Islamist groups. Contributing to these difficulties, and in part caused by them, Islamic State itself now asks its supporters abroad to remain in their countries of origin and act there against “the kuffar [infidel].”

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The group has also seen a dramatic decline in income. Its revenue in 2015 from its crude-oil industry was estimated at $600-$700 million. The current prevailing estimate is that this pace of income has been cut in half, with crude oil revenues for 2016 expected to be roughly $250-$350 million. If revenue from crude oil made up half of Islamic State’s income in 2015, it currently comprises only one-third of its income.

In order to close the gap, IS has raised taxes on local populations in territories it controls. It has made significant cuts in salaries for its fighters and officials — from approximately $300 per month to between $50 and $150, depending on the rank of the “soldier.” It is investing less in civilian infrastructure such as electricity, water, waste removal and courts, and is forced to funnel nearly all its resources to its military efforts.

The jihadist group has also lost many of its top personnel in recent months, with the killing in late August of Abu Mohammad al-Adnani, its spokesman, thought to be the most devastating of these losses. Al-Adnani was not only Islamic State’s spokesman but also its highest-ranking field commander. He was responsible for the planning and execution of terror attacks abroad since the group’s leader, Abu Bakr al-Baghdadi, spends much of his time hiding from American attacks.

All these factors have led Islamic State to change its strategy. Instead of attacks, raids, and taking over new areas of territory, it has moved onto the defensive, strengthening its hold on the places it already controls, digging trenches and trying to survive the devastating aerial bombardments coming mainly from United States forces. Islamic State’s most important region, outside Syria and Iraq, was Libya, where its personnel have suffered harsh military defeats as well.

Yet Islamic State has managed to survive in terms of both logistics and command. Its command and control structure still works (several of its senior commanders were officers in the Iraqi army in Saddam Hussein’s time), and al-Baghdadi continues to set the tone, apparently from his hiding place in the Syrian city of Raqqa. Islamic State’s bureaucratic structure has survived as well. So although Islamic State’s power is on a constant downturn, it is still hard to predict when a more dramatic decline, of the sort that will keep it from working in an organized fashion, will occur.

Should Islamic State be defeated, no one can say which Islamic group will take its place or what will happen to the territories from which it will have to withdraw. It is not at all certain that calm and security will return to the country if the Iraqi army should take Mosul, Iraq’s second-largest city, in the coming months. Tensions still run high between the Sunnis and the Shi’ites, as well as among various Shi’ite groups, over the way the country should be run, as well as its future.

Neither is it known in Syria who can lead the ground war against Islamic State, particularly around Raqqa. The Kurds are not particularly eager, at this stage, to risk heavy losses by attempting to wrest Raqqa from Islamic State.

Islamic State’s “brand” has definitely weakened as far as image goes, though the idea still survives and changes form. While Islamic State’s commanders already admit in various online forums that there will be no caliphate on the ground, they still call for ongoing worldwide terror attacks against the infidel.

As far as this idea goes, it must be said that Islamic State has not been all that successful in carrying out terror attacks abroad. Its terror-attack structure has not succeeded in perpetrating particularly deadly large-scale terror attacks abroad in recent months, though it is quick to take responsibility for terror attacks perpetrated by extremists who are inspired by them but who have no operational link to Islamic State’s command in Syria.

Meanwhile, in Syria, Iran sets the tone

There are hardly any changes on the ground on the Syrian Golan Heights. Low-intensity fighting continues between the supporters of Bashar Assad and Hezbollah and the moderate opposition, as well as supporters of Islamic State (formerly the Yarmouk Martyrs Brigade and currently the Khalid ibn al-Walid Army).

The relatively moderate opposition, together with Jabhat Fateh al-Sham (formerly the Al-Nusra Front), has ceased hostilities against the Druze village of Al-Khadr, which is considered a pro-Assad bastion. Among the reasons for this was Israel’s firm message to the Syrian opposition not to capture or besiege Al-Khadr (due to the close connections between the Druze people living there and the Druze people living in Israel).

The main event in Syria is taking place around Aleppo. The Syrian regime — whose survival is no longer in question — is attempting, together with its Russian and Iranian allies, to complete its capture of Aleppo. It considers doing so critical, at least in terms of its image. It seems that the Russians got burned during the capture of Palmyra, in the fighting against Islamic State, which allowed the opposition in Aleppo to regroup and garner some impressive victories there. This is why the Russians have decided, for the time being, to focus their efforts in Aleppo and Hama on fighting against the moderate opposition and Jabhat Fateh al-Sham, and leave fighting against Islamic State to others.

Troops of the Iranian Revolutionary Guards are also involved in the fighting in Aleppo. Together with the commander of the Russian troops in Syria and the Syrian army, they direct what happens on the ground. At their disposal are Hezbollah troops, Bashar Assad’s army, and a kind of “foreign legion”: three brigades of Shi’ite combat fighters who are neither Syrian nor Lebanese.

One brigade, from Iraq, is made up of troops whom the Iranians recruited to fight in Iraq for pay, and were transferred to Syria. The other two, from Pakistan and Afghanistan, are made up of Pakistanis and Afghanis who tried to immigrate to Iran and were persuaded to join the fighting in Syria with promises (of Iranian citizenship) and threats (of expulsion from Iran), among other things.

Opposing them is a coalition comprising dozens of Sunni groups, the most prominent of which are Ahrar al-Sham and Jabhat Fateh al-Sham, and they, too, act in coordination with one another. In all, 750,000 people are still in Aleppo, of whom 250,000 are besieged in the eastern sections under the opposition’s control.

The damage in Aleppo is severe, mostly in infrastructure and medical treatment. Yet Israeli officials believe that the situation there has not yet reached the point of no return, and that the fighting in Aleppo, or throughout Syria, is nowhere near a decisive outcome. The Russians, too, 14 months after they entered Syria, are realizing that the Syrian opposition is far from giving up, and that they must still engage in an ongoing and costly military effort.