The terror group has reportedly lost control of the last strip of its territory along the Syrian-Turkish border, according to sources and Turkish state-run news agency Anadolu.
"The Turkish border with Syria was cleared Sunday of Daesh terrorists," Anadolu reported.
"The Jarablus-Azaz line is totally under the control of FSA (Free Syrian Army) backed by coalition forces," a Turkish armed forces member told CNN Sunday.
Azaz is another key border city that was formerly held by ISIS.
The developments would be a major setback for ISIS, choking off supply lines for the terror group.
The UK-based Syrian Observatory for Human Rights said Sunday that the terror group has effectively lost its contact with the outside world, after losing the remaining border villages between the Sajur River in the southern suburbs of Jarablus and Al-Rai.
Turkey's campaign south of border
These Turkish incursions mark a new phase in Operation Euphrates Shield, a campaign launched last month to improve security and clear the Sunni terror group from the border region.
Turkey was pressed into action against ISIS
by the surge of suicide attacks in Turkey, as well as the terror group's use of safe houses and "informal" financial services on Turkish soil.
On Saturday, Turkey sent tanks and armored vehicles into the Syrian border town of Al-Rai, effectively opening a new front in its campaign against ISIS, Turkish state media reported. Al-Rai is about 55 kilometers west of Jarablus.
On Sunday, a dozen other villages near the Turkish border were captured by the Free Syrian Army backed by Turkish military, a Turkish armed forces member told CNN.
The Turkish military said at least 300 ISIS targets have been hit since Operation Euphrates Shield began on August 24.
Turkey and Kurdish militias
Turkey's government has signaled that its offensive will not only target ISIS but also the Syrian Kurdish YPG, who are viewed as an equal threat.
The question of the Kurdish militias has complicated cooperation between Turkey and the United States, NATO allies and partners in their fight against ISIS in Syria.
Turkey is opposed to Washington's support for the Syrian Kurdish YPG militia, one of the most effective forces on the ground in the fight against ISIS, viewing them as indistinct from outlawed Kurdish militants fighting a long insurgency in southeast Turkey.
Turkish authorities are also building a wall to boost security along a stretch of its border with Syria, Anadolu reported
. The wall is being erected from Karkamis, a Turkish town across the border from Jarablus, to Suruc, which lies across from the Syrian town of Kobane.
US forces used a new weapon -- the high mobility artillery rocket system, or HIMARS -- against an ISIS target in northern Syria Saturday night, a coalition official confirmed to CNN. The system -- designed to reduce potential collateral damage as it impacts at a high angle and has a relatively small blast radius -- was fired out of southern Turkey, a US official said.
US, Russia talks end unresolved
High-level talks between the US and Russia aimed at ending violence in the war-torn country ended without an agreement,
a US official said Monday.
The talks, between US Secretary of State John Kerry and his Russian counterpart Sergey Lavrov, on the sidelines of the G20 summit in Hangzhou, China, failed to resolve differences and left the Syrian question unanswered, the official said.
Kerry and Lavrov were working to negotiate a plan that would have boosted military cooperation between the two nations in an effort to better target terrorists and prevent civilian deaths, but negotiations have ended for now.
"There are still issues to resolve," the US official said.
On Sunday, cautious optimism had prevailed that a deal could be struck between Washington and Moscow, long at odds over policy in Syria. Kerry and Lavrov had been working "around the clock" to come to an agreement, US President Barack Obama told reporters.
Russian forces have aligned with Syrian President Bashar al-Assad
to target US-backed opposition fighters that Moscow and Damascus claim are terrorists. The campaign has spurred a humanitarian crisis and caused millions of Syrians to flee for Europe.
The US had hoped to align with Russia to identify terrorist targets, including ISIS and the Nusra Front, a group formerly tied to al-Qaeda. Officials hope a ceasefire will help advance talks on a political transition that would lead to the resignation of Syrian leader Bashar al-Assad.
The crisis has been a vexing topic of discussion at the G20 meeting of world leaders in Hangzhou, China, where the United States and Russia, at odds on the question of support for the Syrian regime, continue to work to strike a deal on resolving the conflict.
On Sunday, US Secretary of State John Kerry told reporters that he and Russian Foreign Minister Sergey Lavrov would continue work on a deal, but that "a couple of tough issues" persisted.
Previous diplomatic efforts have resulted in warring parties agreeing to a "cessation of hostilities," a brief pause in the fighting allowing for humanitarian aid to be delivered to suffering civilian populations. But talks have so far failed to yield a more lasting ceasefire.
Obama said after meeting with Turkish President Recep Tayyip Erdogan Sunday that the two leaders had discussed a peaceful transition of power in Syria. Both the United States and Turkey are in favor of regime change in the war-torn country.
Syrian government forces recapture areas in Aleppo
Meanwhile the war grinds on.
Syrian government forces backed by Hezbollah, Iranian militia and other allies on Sunday sought to reimpose a siege on rebel-held areas of eastern Aleppo, according to the UK-based Syrian Observatory for Human Rights and other sources.
The areas recaptured include the Armament and Airforce Technical College in southwestern Aleppo.
"We can't now cross the road to Aleppo even on foot. Aleppo is besieged again," a rebel fighter near the battle zone told CNN.
Syria's state-run news agency SANA confirmed the report, adding that "army units, in cooperation with allied forces, carried out a special and swift military operation, establishing full control over Armament Academy and expanding their control in the area of military academies to the south of Aleppo city."
SANA said "Syrian army air force carried out intensive air strikes against gatherings and fortifications of Jaish al-Fateh terrorists in Aleppo countryside, destroying a number of their vehicles and killing scores of them and injuring others."
Syrian government forces backed by Russian air power have been pounding Aleppo relentlessly for months now in an effort to take back the eastern part of the city, which has been in rebel hands for nearly four years. Aleppo has been a major battlefield in Syria since 2011, with fierce fighting between rebel groups and regime forces.
Aleppo was the country's largest city before the war and a vital economic hub. It is now a shadow of its former self after being flattened by constant aerial bombardment. Last month, the image of a 5-year-old Syrian boy
rescued after an airstrike leveled his house reverberated around the world.
The loss of Aleppo would be a devastating symbolic blow to the rebels
, sending a signal that President Bashal al-Assad has reclaimed his hold over the country and that the rebel movement is on its last legs.