Kurdish fighters launched a series of attacks against Islamic State positions Tuesday in Iraq, supported by the Iraqi military and the U.S.-led coalition.
U.S. Central Command said 11 airstrikes Monday and Tuesday were focused largely on the Islamic State group's stronghold in northwest Iraq. Four of those strikes also hit militant vehicles and fighting positions near the Mosul Dam as well as outside Baghdad.
The air campaign also included 11 strikes in Syria, destroying militant artillery and rocket launchers on the outskirts of Kobani, also known as also known as Ain al-Arab.
Meanwhile, Britain has launched its first air attack against the Islamic State in Iraq.
The Ministry of Defense announced on social media Tuesday that its fighter jets hit a militant heavy weapons post. The airstrikes mark Britain's debut in the U.S.-led coalition, which includes Arab and European militaries.
The two-week offensive against the Islamic State group has sent more than 160,000 refugees across the border into Turkey, which reinforced its side of the frontier near Kobani on Monday.
Peshmerga take border crossing
Iraqi Kurdish peshmerga fighters took control of the Rabia border crossing in a battle that began before dawn, an Iraqi Kurdish political source told Reuters.
They also won the support of members of a major Sunni tribe, in one of the biggest successes since U.S. forces began bombing the Islamists. The victory was also achieved with help from Kurds from the Syrian side of the frontier, a new sign of cooperation across the border.
The ability to cross the frontier freely has been a major tactical advantage for Islamic State fighters on both sides. Fighters swept from Syria into northern Iraq in June and returned with heavy weapons seized from fleeing Iraqi government troops, which they have used to expand their territory in Syria.
“It's the most important strategic point for crossing,” a source told Reuters.
The participation of Sunni tribal fighters in the battle against Islamic State militants could prove as important a development as the advance itself.
Members of the influential Shammar tribe, one of the largest in northwestern Iraq, joined the Kurds in the fighting, a tribal figure told Reuters.
“Rabia is completely liberated. All of the Shammar are with the Peshmerga and there is full cooperation between us,” said Abdullah Yawar, a leading member of the tribe.
Yawar said the cooperation was the result of an agreement with Iraqi Kurdish leader Masoud Barzani after three months of negotiation to join forces against the “common enemy.”
Rabia controls the main highway linking Syria to Mosul, the biggest city in northern Iraq, which Islamic State fighters captured in June at the start of a lightning advance through Iraq's Sunni Muslim north that jolted the Middle East.
Considered a success
If Rabia can be held, its recapture is one of the biggest successes since U.S.-led forces started bombing Islamic State targets in Iraq in August.
It is one of two main border crossings between militant-held parts of the two countries, control of which has allowed Islamic State fighters to declare a single Caliphate on both sides.
Washington expanded the air campaign to Syria last week in an effort to defeat the fighters who have swept through Sunni areas of both countries, killing prisoners, chasing out Kurds and ordering Shi'ites and non-Muslims to convert or die.
Washington hopes the strikes, conducted with help from European allies in Iraq and Arab air forces in Syria, will allow government and Kurdish forces in Iraq, and moderate Sunnis in Syria, to recapture territory.
Late last week, Britain's parliament approved combat operations in Iraq. On Tuesday, Britain said its Tornado warplanes had launched their first attacks against Islamic State fighters, targeting a heavy-weapons position that was endangering Kurdish forces and subsequently attacking an Islamic State armed pickup truck in the same area.
In Iraq, a coalition of Iraqi army, Shi'ite militia fighters and Kurdish troops have been slowly recapturing Sunni villages that had been under Islamic State control south of the Kurdish-held oil city of Kirkuk.
An Iraqi security official said two villages near Daquq, 40 kilometers south of Kirkuk, were liberated by Peshmerga forces.
Islamic State fighters had used positions in the villages to fire mortars at neighboring Daquq, a town populated mainly by ethnic Turkmen Shi'ite Muslims.
When Kurdish fighters entered the villages they were empty, the security official said.
Peshmerga fighters, Iraqi army troops and pro-government militia were advancing north from the Peshmerga-held city of Tuz Khurmatu to drive Islamic State fighters out of the countryside that surrounds Kirkuk, the official said. He credited U.S.-led air strikes with helping the Peshmerga clear the two villages.
The official credited U.S.-led airstrikes with helping the peshmerga clear the two villages.
Peshmerga secretary-general Jabbar Yawar estimated the Iraqi Kurds had retaken about half the territory they lost when the militants surged north toward the regional capital, Irbil, in early August, an advance that helped to prompt the U.S. airstrikes.
In addition to aiding the Kurds in the north, U.S. airstrikes have targeted fighters west of Baghdad and on its southern outskirts.
“We believe the U.S. airstrikes have helped in containing Islamic State's momentum,” said lawmaker Mowaffak al-Rubaie, a former head of Iraq's advisory security council.
Fight for Kobani continues
Islamic State fighters have also laid siege to Kobani, a Kurdish city on Syria's border with Turkey that has become a flashpoint for the battle against Islamic State militants.
Ocalan Iso, deputy commander of the Kurdish forces defending the town, told Reuters that Kurdish troops had battled Islamic State fighters armed with tanks through the night and into Tuesday.
The Syrian Observatory for Human Rights, a body that monitors the war with a network on the ground, said U.S.-led strikes had hit Islamic State positions west of Kobani.
Just outside Kobani, Islamic State militants captured the deserted Kurdish village of Siftek on Tuesday and appeared to be using it as a headquarters from which to launch attacks on Kobani itself, The Associated Press reported.
The Observatory said Islamic State now controls 325 out of 354 villages on the rural outskirts of Kobani.
With the United States now conducting what it said are "near continuous" strikes in both Iraq and Syria, a Washington-based think-tank warned that the costs of the campaign to the U.S. taxpayer could swiftly escalate.
U.S. aircraft have flown roughly 4,100 sorties in the air war against the jihadists in Iraq and Syria since August, including surveillance flights, refuelling runs and bombing raids, a military officer told the French news agency AFP.
The Center for Strategic and Budgetary Assessments estimated that when U.S. airstrikes against Islamic State militants in Syria got under way last week, Washington had already spent as much as 735 million euros ($930 million) on the campaign against the Islamic State group.
If airstrikes continue at a moderate level, the cost will run at between $200 million and $320 million a month, but if they are conducted at a higher pace, the monthly cost could rise to as much as $570 million, the think-tank projected.
Some materials for this report came from Reuters, AFP and AP.