A Russian and Syrian offensive on Idlib province, a center of the opposition forces in the long-running Syrian War, killed over a dozen civilians over the weekend.

Late on Saturday night, Russian jet fighters and Syrian combat helicopters attacked the northwestern Syrian province of Idlib, which is considered to be the last stronghold of armed opposition fighters against Russia-backed Syrian President Bashar al-Assad.

The strikes claimed the lives of 18 civilians and caused the injury of dozens others, international sources reported. The Syrian Observatory for Human Rights, a monitor group based in London, confirmed that the areas targeted are densely populated by civilian residents. “Russian and Syrian regime attacks on some villages in Idlib have increased since mid-November,” Rami Abdulrahman, director of the monitoring group, said.

Dubbing the deadly attack as a massacre, Abdulrahman noted that Saturday’s raids were the largest since the escalation started. According to Aljazeera English-language news website, eight children and two women were among the dead when the strikes hit the villages of Balyoun and Bara, where rebels are said to be largely concentrated.

Civilians Displaced

During the past several weeks, thousands of residents in Idlib have reportedly fled their homes because of an increase in military attacks, the Syrian Observatory for Human Rights, recorded.

Another rights group, Humanitarian Response, noted that more than 92,000 civilians from southern Idlib and the northern Hama provinces have been displaced.

Idlib itself is home to 3 million Syrians and is said to be the last stronghold of the insurgents who have opposed President Bashar Assad, since the outbreak of the Syrian civil war in 2011.

The insurgents are believed to be part of the Hayat Tahrir al-Sham, or the Board of Liberation of Levant, a former affiliate of the al-Qaeda Islamist militant group in Syria.

Syria, Russia and Turkey had agreed in September 2018 to hold off a Syrian plan to carry out a major offensive on Idlib and other areas adjacent to Turkey. Turkey agreed to remove some of the rebel groups that are affiliated with al-Qaeda, but failed to do so.

In early October Turkish military forces, along with allied Syrian militia fighters, carried out an offensive against the Kurdish-led Syrian Democratic Forces in parts of northeast Syria, following U.S. President Donald Trump’s order to remove U.S. forces who were allied with the Kurds from the area.

Turkey’s fight against the Kurds stems from Tehran’s long fight against separatist Kurdish fighters, who have long sought a national home of their own, away from the central government of Turkey.

For about four months now, Syrian troops have carried out military attacks on Idlib, within what Assad has described as his vow to restore every inch of the Arab Syrian Republic.

Syria’s Civil War

Since 2011 the Arab Republic of Syria, home to nearly 19 million residents, has endured a civil war sparked by mass protests demanding social and economic reforms.

Since then, hundreds of thousands have been killed and injured, while millions more have been displaced. In recent years, Russia has become a key ally for the Syrian government, intervening in the war and helping Syria defeat the armed opposition groups.