The divisions within the rank and file of the terrorist organization seem to be growing as it has lost all its territory and is now surrounded in a border town, with the US-backed Kurdish militias pressing their offensive from the west on the Syrian side and the Iran-backed militias from the east on the Iraqi side of the border.
Moreover, tens of thousands of Islamic State jihadists and civilians have been killed in the airstrikes conducted by the US-led coalition against the Islamic State and the ground offensives by the Iraqi armed forces and allied militias in Iraq and the Kurdish-led Syrian Democratic Forces in Syria.
Furthermore, due to frequent desertions, the number of fighters within the Islamic State’s ranks has evidently dwindled. But a question would naturally arise in the minds of curious observers of the war against the Islamic State in Iraq and Syria that where did the remaining tens of thousands of Islamic State’s jihadists vanish?
The riddle can be easily solved, though, if we bear in mind that although Idlib Governorate in Syria’s northwest has firmly been under the control of Hayat Tahrir al-Sham (HTS) led by al-Nusra Front since 2015, its territory was equally divided between Turkey-backed rebels and al-Nusra Front.
In a brazen offensive last month, however, the al-Nusra jihadists completely routed Turkey-backed militants even though the latter are supported by a professionally trained and highly organized and disciplined military of a NATO member Turkey. And al-Nusra Front now reportedly controls 70% territory in Idlib Governorate.
The reason why al-Nusra Front has been easily able to defeat Turkey-backed militants appears to be that the ranks of al-Nusra Front have now been filled by hardcore jihadist deserters from the Islamic State after the fall of the latter’s “caliphate” in Mosul in Iraq and Raqqa in Syria.
The merger of al-Nusra Front and Islamic State in Idlib doesn’t come as a surprise, though, since the Islamic State and al-Nusra Front used to be a single organization  before a split occurred between the two militant groups in April 2013 over a leadership dispute.
Regarding the nexus between Islamic jihadists and purported “moderate rebels” in Syria, while the representatives of Free Syria Army (FSA) were in Washington in January last year, soliciting the Trump administration to restore the CIA’s “train and equip” program for the Syrian militants that was shuttered in July 2017, hundreds of Islamic State’s jihadists joined the so-called “moderate rebels” in Idlib in their battle against the advancing Syrian government troops backed by Russian airstrikes to liberate the strategically important Abu Duhur airbase, according to a January last year’s AFP report authored by Maya Gebeily.
The Islamic State already had a foothold in neighboring Hama province and its foray into Idlib was an extension of its outreach. The Islamic State captured several villages and claimed to have killed two dozen Syrian soldiers and taken twenty hostages, according to the report.
Though the AFP report titled “Four years and one caliphate later, Islamic State claims Idlib comeback”  has been taken down by Yahoo News, because it mentioned that on January 12, 2018, the Islamic State officially declared Idlib one of its “Islamic emirates.”
The reason why the AFP report has been redacted appears to be that it did not meet the editorial line of the mainstream media, as it mentioned Idlib, which is surrounded by the Syrian government troops, as an “Islamic emirate” of the Islamic State, which could provide a pretext to the Syrian armed forces backed by Russian airstrikes to mount an offensive against the jihadists in Idlib Governorate.
Nevertheless, in all likelihood, some of the Islamic State’s jihadists who joined the battle in Idlib in January last year were part of the same contingent of thousands of Islamic State militants that fled Raqqa in October 2017 under a deal brokered  by the US-backed Syrian Democratic Forces (SDF).
In fact, one of the main objectives of the deal was to let the jihadists fight the Syrian government forces in Idlib and elsewhere in Syria, and to free up the Kurdish-led SDF in a scramble against the Syrian government troops to capture oil and gas fields in Deir al-Zor in eastern Syria and the border posts along Syria’s border with Iraq.
Notwithstanding, according to a December 29 report by RT :
“A high-ranking Turkish delegation arrived in Moscow on December 29, only a day after international media broke news of Kurdish militias inviting Syrian forces to enter Manbij before the Turks do. Syria’s military proclaimed they ‘raised the flag’ over Manbij, but there have been no independent reports confirming the moving of troops into the city.”
The report notes:
“The Saturday Moscow meeting was key to preventing all actors of the Syrian war from locking horns over the Kurdish enclave. Obviously, Turkey will insist that it is their forces that should enter Manbij, Russia will of course insist the city should be handed over to Assad’s forces, Kirill Semenov, an Islamic studies expert with Russia’s Institute for Innovative Development, told RT.”
The report further adds:
“Realpolitik, of course, plays a role here as various locations across Syria might be used as a bargaining chip by all parties to the conflict. Semenov suggested the Turks may agree on Syrian forces taking some parts of Idlib province in exchange for Damascus’ consent for a Turkish offensive toward Manbij or Kobani.”
It becomes abundantly clear after reading the RT report that a land swap agreement between Ankara and Damascus under the auspices of Moscow is in the works to avoid standoff over Arab-majority towns of Manbij and Kobani which have been occupied by the Kurds since August 2016 and January 2015, respectively.
The regions currently being administered by the Kurds in Syria include the Kurdish-majority Qamishli and al-Hasakah in northeastern Syria along the border with Iraq, and the Arab-majority towns of Manbij to the west of the Euphrates River in northern Syria and Kobani to the east of the Euphrates River along the southern Turkish border.
The oil- and natural gas-rich Deir al-Zor governorate in eastern Syria has been contested between the Syrian government and the Kurdish-led Syrian Democratic Forces, and it also contains a few pockets of the remnants of the Islamic State militants alongside both eastern and western banks of the Euphrates River.
The Turkish “East of Euphrates” military doctrine basically means that the Turkish armed forces would not tolerate the presence of the Syrian PYD/YPG Kurds – which the Turks regard as “terrorists” allied to the PKK Kurdish separatist group in Turkey – in Manbij and Kobani, in line with the longstanding Turkish policy of denying the Kurds any territory in the traditionally Arab-majority areas of northern Syria along Turkey’s southern border.
The aforementioned Moscow-brokered agreement would likely stipulate that Damascus would permit Ankara to mount offensives in the Kurdish-held towns Manbij and Kobani in northern Syria in return for Ankara withdrawing its militant proxies from Maarat al-Numan, Khan Sheikhoun and Jisr al-Shughour, all of which are strategically located in the south of Idlib Governorate.