The Syrian Democratic Forces (SDF) on Wednesday (May 10th) captured the northern Syrian city of al-Tabqa and its nearby dam from the "Islamic State of Iraq and Syria" (ISIS).

The Arab-Kurd opposition alliance said it had "completely liberated" al-Tabqa and the adjacent dam after weeks of fierce fighting, AFP reported.

"The SDF were able to deploy onto the dam itself during the night," Syrian Observatory for Human Rights head Rami Abdel Rahman said.

"But civilians are still unable to enter some parts of al-Tabqa because of explosives" left by ISIS, he added.

"Combing operations are ongoing to ensure that the city is clear," SDF spokesman Talal Sello said.

De-mining teams are removing explosives from the main streets first, said Wahid al-Khalaf of the Thuwar al-Raqa Brigade, an Arab faction within the SDF.

Then they will start clearing houses and agricultural fields in preparation for the return of civilians, he told Diyaruna.

The capture of al-Tabqa is being hailed as a strategic victory for the SDF, and will enable the alliance to advance on al-Raqa and fulfill the objective of the ongoing Operation Wrath of the Euphrates.

Al-Tabqa sits on the Euphrates River as well as on a strategic supply route about 55 kilometres west of al-Raqa city, the capital of ISIS's so-called caliphate.

The battle for al-Tabqa

Coalition warplanes have pounded al-Tabqa and nearby ISIS positions for weeks as part of the SDF's offensive for al-Raqa.

The SDF, supported by coalition airstrikes and special forces advisers on the ground, first entered al-Tabqa on April 24th, advancing north and cornering the group in two neighbourhoods near al-Tabqa dam.

But ISIS mounted a fierce resistance, using car bombs, snipers, and weaponised drones.

By Sunday (May 7th), the SDF had captured more than 90% of al-Tabqa and was battling dozens of ISIS fighters cornered in the northern neighbourhoods of the city near the dam.

An SDF commander inside al-Tabqa on Sunday said the operation had been progressing slowly "because of the presence of civilians being used as human shields by ISIS", adding that SDF forces were trying to advance "carefully and accurately".

Al-Tabqa's population has dwindled from 250,000 before Syria's conflict erupted in 2011 to 75,000. After ISIS overran the area in 2014, around 10,000 ISIS fighters and their families came to live in the city, which served as a key command base and housed the group's main prison.

A convoy of about 50 cars carrying ISIS fighters and their families was seen leaving al-Tabqa towards the city of al-Raqa on Tuesday night, SDF fighter al-Khalaf said.

"There were at least 300 people [in the convoy], including the wives of some ISIS fighters and the group's wounded fighters," he said.

Assessing damage to the dam

A repair team was on standby on Thursday, awaiting permission from the SDF to enter and assess any damage to al-Tabqa dam -- Syria's largest.

A source who works with the dam's technicians said they had fled the structure as fighting drew near in recent days.

The dam fell into the hands of the Syrian opposition in February 2013, before ISIS seized control of the city and province of al-Raqa in early 2014.

The UN warned at the time that damage to the dam "could lead to massive scale flooding across al-Raqa and as far away as Deir Ezzor".

Syrian farmers near the Euphrates said they were terrified ISIS would blow up the dam to defend al-Raqa, flooding their villages in the process.

The Euphrates is the main source of water for agriculture and livestock in the region, and the dam, also known as the Euphrates dam, and al-Thawra dam, has given al-Raqa an important role in the Syrian economy.

Arming the YPG

On Wednesday, the US said it will soon start delivering weapons to the Kurdish People's Protection Units (YPG), which makes up the bulk of the SDF, a US military spokesman said.

A first consignment of weapons is already in place for delivery and could be dispatched to the Kurds "very quickly", said Col. John Dorrian, a military spokesman for the international coalition in Baghdad.

The White House has already on Tuesday given the Pentagon the green light to deliver weapons and equipment to the YPG "to ensure a clear victory over ISIS in al-Raqa".

The YPG hailed the move as "historic" and said it would now play "a more influential, powerful, and decisive role" in fighting ISIS.

Until Tuesday, official US policy was to supply weapons only to the Arab components of the SDF.

"The US decision to arm the YPG... is important and will hasten the defeat of terrorism," SDF spokesman Talal Sello said.

Sello said the US announcement "is the result of the effectiveness of the YPG and SDF in the fight against terrorism".

Waleed Abu al-Khair in Cairo contributed to this report.