Syria's government has condemned a Turkish military offensive in northern Syria, just hours after Turkish tanks and armored personnel carriers advanced into a part of Syria that has been under the control of Islamic State (IS) militants since July 2013.
Ankara-backed Syrian rebels from the Syria Free Army also were taking part in the operation, which was being supported by U.S. and Turkish air strikes and was aimed at clearing IS militants from the border area.
The operation began just before dawn on August 24 as U.S. Vice President Joe Biden was traveling to Ankara for talks with senior Turkish officials -- including President Recep Tayyip Erdogan and Prime Minister Binali Yildirim.
A senior U.S. official aboard Biden’s plane told reporters on August 24 that Washington was “in sync” with Turkey on plans.
Syria's government described the military incursion as a "blatant violation" of Syrian sovereignty and demanded an end to what it said was "aggression" being carried out under the pretext of fighting terrorism.
Damascus said in a statement that "any move to combat terrorism on Syrian territories should have been coordinated with the Syrian government and army."
It said: "Fighting terrorism cannot be undertaken by ousting [IS]...and replacing it with other terrorist organizations directly backed by Turkey."
As Turkish armored forces began crossing the border into Syria, Biden arrived in Ankara and went into talks with parliamentary speaker Ismail Kahraman.
Biden was scheduled to meet Erdogan and Yildirim later in the day -- with their talks expected to focus on deteriorating relations between Ankara and its NATO allies since a failed July 15 military coup in Turkey.
The United States and Europe have criticized a broad crackdown by Ankara against Erdogan’s political opponents since the coup.
Erdogan said Turkey’s request for Washington to extradite exiled Turkish cleric Fethullah Gulen -- accused by Erdogan of orchestrating the attempted coup -- would be a key issue in the talks.
Washington has said it would need evidence of the U.S.-based cleric’s involvement in the coup. Gulen has denied any involvement in the plot.
But Erdogan said on August 24 he would tell Biden that the United States has no excuses and must hand over Gulen.
Another issue expected to be discussed during Biden’s one-day visit to Ankara is the role in the fight against IS militants that Syrian Kurdish fighters should have.
Washington supports Syrian Kurdish fighters from the Democratic Union Party (PYD) and sees them as vital to the U.S.-led coalition’s strategy of combating IS militants.
But Ankara accuses the PYD of being aligned with Turkish Kurdish rebels from the outlawed Kurdistan Workers Party (PKK).
Finally, recent efforts by Erdogan’s government to improve relations with Russia -- steps that have contributed to the worsening of ties between Turkey and its NATO allies -- also were expected to be addressed by Biden.
Ahead of Biden’s arrival in Ankara, the joint Turkish-U.S. military operation on August 24 was focusing on the IS-held Syrian border town of Jarablus and the surrounding area.
Turkish Foreign Minister Mevlut Cavusoglu vowed via Twitter that the "cleansing" of Jarablus would mark a turning point in the fight against IS.
By midday, Turkish artillery and warplanes, together with U.S. warplanes and guided by Turkish special forces inside Syria, had launched more than 200 air and artillery strikes against IS targets in and around Jarablus.
Syrian opposition activists and Turkish state television reported that fighters from the Turkey-backed Free Syria Army had advanced into Jarablus during the early afternoon. Meanwhile, correspondents reported seeing more than a dozen Turkish tanks cross from Turkey into northern Syria as part of the operation.
Erdogan said on August 24 that the conflict in Syria is the main reason Turkey faces terrorist attacks in its territory.
He vowed that all IS fighters would be cleared from parts of northern Syria that border Turkey.
Erdogan also said no one can view the Syrian problem independently from Turkey’s internal affairs.
Turkish Interior Minister Efkan Ala said Turkey also sees a threat from what he described as other “terrorist” organizations -- a reference to Syrian Kurdish fighters from the PYD.
After reports that Turkey also was firing artillery at Syrian Kurdish fighters from the PYD, the group's leader, Salih Muslim, said Turkey had entered “the Syrian quagmire” and would be defeated along with IS militants.
Turkish Foreign Minister Mevlut Cavusoglu said on August 24 that Syrian Kurdish fighters must return to the eastern side of the Euphrates River or Turkish military forces would “do what is necessary.”