Russia and Turkey had agreed on two conditions to form a demilitarized zone around the Syrian idlib: the withdrawal of all heavy weapons and the withdrawal of all rebels from the buffer zone. The second condition has now apparently let the radical Islamic militias in the region pass. None of the groups should have left the rebel stronghold so far, said the Syrian Observatory for Human Rights on Monday.

The opposition observatory gets its information from a network of doctors and activists in Syria. The information is usually not independently verifiable. However, they have proven to be reliable in the past.

According to the agreement between Ankara and Moscow, the withdrawal should have taken place by Monday. The first part of the agreement had obviously been respected. According to Turkey and the Syrian Observatory for Human Rights, all heavy weapons have been withdrawn. The deadline had already expired last Wednesday.

Radical militia wants to continue the fight

Russia as an ally of the Syrian government and Turkey as supporters of the rebels had agreed in September on the demilitarized buffer zone, which was up to 20 kilometers wide. It should prevent a government offensive on Idlib.

The region around the city of the same name in the northwest of the civil war country is the last major rebel stronghold of Syria. There live about three million civilians, almost half of them refugees. Aid organizations had warned that an Idlib offensive could lead to a new humanitarian disaster.

Radical militia Haiat Tahrir al-Sham (HTS) announced Sunday night to continue their struggle. "We will not deviate from the path of jihad to realize the goals of our revolution," it says in a statement. The group, like other rebels, wants to topple Syrian President Bashar al-Assad. The formerly known as the Al-Nusra Front militia is particularly strong in Idlib. She has connections to the terrorist network Al-Qaida.

Syria's foreign minister wants to give Russia time to assess

Syrian Foreign Minister Walid al-Moualem expressed concern: "We can not keep quiet about the ongoing situation in Idlib if the Al-Nusra Front refuses to comply with the agreement, but Syria will give its ally Russia time to to assess whether Turkey and the Syrian armed opposition had fulfilled their part of the deal.

"We've always said that Idlib, like any other province, has to come under Syrian rule again," ad-Moualem said. "We prefer to achieve this through peaceful means, through reconciliation, but if not, there are other possibilities."