BEIRUT -- Syrian government forces advanced to within 6 miles of the Islamic State-occupied Tabqa air base in the northern part of the country on Sunday, part of a push to try to unseat the extremist group from its de facto capital, Raqqa.
Government forces recaptured the nearby Thawra oil field from the militant group, according to Syrian journalist Eyad al-Hosain, who is embedded with the army. Activists said Sunday's government assault was accompanied by an aerial campaign on the town of Tabqa, 5 miles north of the air base. The activist group Raqqa is Being Slaughtered Silently, which smuggles news out of Islamic State-held territory, reported that fighter jets struck the town with cluster munitions, killing at least 10 civilians.
The Tabqa base, 28 miles from Raqqa, holds strategic and symbolic value in the government campaign on the Islamic State capital. It was the last position held by government forces in Raqqa province before Islamic State militants overran it in August 2014, killing scores of detained soldiers in a massacre they documented on video. Raqqa itself became the militants' first captive city.
A Syrian opposition coalition, meanwhile, called on Turkey to investigate the deaths of at least eight Syrian refugees, including four children, who the coalition said were shot dead by border guards Saturday night while trying to cross the frontier.
A statement by the National Coalition of Syrian Revolution and Opposition Forces accused Turkish border guards of firing at a group of civilians trying to cross from Kherbet al-Jouz in northwestern Syria into Turkey's Hatay province, killing 11 people.
The coalition, which relies on Turkish political and financial support, said the fatal shooting "clashes with the generosity displayed by the Turkish government and brotherly people toward displaced civilians."
The Britain-based Syrian Observatory for Human Rights put the death toll at eight. The Local Coordination Committees, an activist network, said at least one of those trying to cross was from Jarablus, a northern Syrian town under Islamic State control.
A senior Turkish official said Turkey was unable to independently verify the claims regarding the shooting, but said authorities were investigating.
"Turkey provides humanitarian assistance to displaced persons in northern Syria and follows an open-door policy -- which means we admit refugees whose lives are under imminent threat," said the official, speaking on condition of anonymity in line with government regulations.
Later Sunday, the Turkish Foreign Ministry issued a statement denying that border guards had fatally shot Syrians trying to cross illegally into Turkey.
The Syrian war has pushed more than 2.7 million refugees into Turkey, according to the United Nations. Turkey has tightened security along its border in recent months to prevent further inflows. The Observatory says border guards have shot dead 60 refugees trying to cross since the start of this year.
Elsewhere, a suicide blast targeted the entrance to a park in the Syrian city of Qamishli, which is shared between government and Kurdish forces, killing three people, an hour after a memorial was held there for victims of the 1915 Armenian genocide.
"Had the bombing taken place earlier, there would have been a massacre," Qamishli resident and writer Suleiman Youssef said by telephone. Qamishli lies on Syria's northern border with Turkey.
And Hezbollah's Al-Manar TV station broadcast footage of a fierce aerial and artillery campaign against Syrian rebels, driving the militants to abandon their positions in the thick of the battle.
It said the footage was from the southern Aleppo countryside. Activists reported Saturday that rebels in coordination with al-Qaida militants managed to take two towns in the area, further threatening the government's supply route to its neighborhoods in divided Aleppo city. Hezbollah has sent thousands of fighters to Syria to back President Bashar Assad's forces and has played a key role in a string of government victories.
The Syrian Observatory for Human Rights said 86 pro-government fighters were killed in four days of fighting there. Al-Manar said government forces killed 167 militants, including some two dozen leaders.
Russian Soldier Dies
Russia's Defense Ministry said Sunday that a Russian soldier has died of wounds he suffered in a militant suicide attack in Syria, the military's 11th casualty since the start of its campaign there.
Sgt. Andrei Timoshenkov died at a hospital at the Russian base in Syria, the ministry said. It said Timoshenkov was protecting an area where the Russian military was handing out humanitarian aid to residents in Homs province on Wednesday and opened fire to stop a vehicle speeding toward the site. The car, rigged with explosives for a suicide attack, blew up, wounding the serviceman. He died the next day in a hospital.
So far eight Russian servicemen have died from enemy fire in Syria. Two others were killed in a helicopter crash, and one killed himself.
The Russian military on Sunday also rejected the Pentagon's accusations that it had deliberately targeted U.S.-backed Syrian opposition forces, arguing that the U.S. had failed to warn about their locations.
Maj. Gen. Igor Konashenkov, a Russian Defense Ministry spokesman, said in an email Sunday that the area targeted in the strike was more than 180 miles away from locations earlier designated by the U.S. as controlled by legitimate opposition forces.
U.S. military officials in a videoconference with their Russian counterparts on Saturday expressed "strong concerns" about Thursday's airstrikes on the At-Tanf garrison, close to the border with Jordan. The attacks hit fighters who are signatories to a nationwide cease-fire.
"Russia's continued strikes at At-Tanf, even after U.S. attempts to inform Russian forces through proper channels of ongoing coalition air support to the counter-ISIL forces, created safety concerns for U.S. and coalition forces," the Pentagon said in a statement, using an acronym for the Islamic State.
Konashenkov retorted that the Russian military had warned the U.S. in advance about the planned strike, but the Pentagon had failed to provide coordinates of legitimate opposition forces, "making it impossible to take measures to adjust the Russian air force action."
He added that the Russian military had proposed months ago to share information about locations of various forces involved in military action in Syria to create a comprehensive map, but the Pentagon hasn't been forthcoming.
On a conciliatory note, he added that Saturday's video conference with the Pentagon was "constructive," reflecting a shared desire "to improve coordination in fighting terrorist organizations in Syria and avoid incidents while conducting military operations there."
The video conference was held as part of bilateral communication channels intended to prevent deadly accidents in the crowded skies over Syria.
Russia has conducted an air campaign in Syria since September, helping Assad's forces win back some ground. Russian President Vladimir Putin pulled back some of Russia's warplanes in March in what he described as a move to help encourage peace talks, but the military has maintained a strong presence at the Hemeimeem air base in Syria's coastal province of Lattakia, Assad's Alawite heartland.
Both Russia and the U.S., the co-sponsors of the Syria peace process, have tried to promote a settlement of the more than five-year conflict, but those efforts have stalled as fighting surges in Syria. Russia says some U.S.-backed rebels have links to a local affiliate of al-Qaida, which along with the Islamic State militant group is excluded from the cease-fire negotiated in February. Russia says the U.S.-backed rebels are legitimate targets if they don't break off those ties.
Information for this article was contributed by Philip Issa, Albert Aji, Dominique Soguel and Vladimir Isachenkov of The Associated Press; and by Henry Meyer of Bloomberg News.
A Section on 06/20/2016