DAMASCUS (Dispatches) -- Turkey launched a military aggression against northern Syria on Wednesday with airstrikes and artillery fire reported along the border.
President Recep Tayyip Erdogan announced the start of the incursion on Twitter, labelling it "Operation Peace Spring".
It triggered criticism from Western countries who have allied with Kurdish SDF militants in Syria. An AFP correspondent reported Turkish artillery fire in the Ras al-Ain border area and explosions as warplanes flew overhead.
Kurdish militants said at least two civilians were killed. SDF fighters armed with rocket launchers were seen deploying in the area, as Kurdish authorities called up civilians to defend against the assault, AFP reported.
The so-called Syrian Observatory for Human Rights war monitor said airstrikes and artillery fire also hit the Tal Abyad border region further west.
The SDF called on the international community to impose a no-fly zone to protect against "an imminent humanitarian crisis".
Erdogan said the operation would target both Kurdish militants and Daesh. "Our mission is to prevent the creation of a terror corridor across our southern border, and to bring peace to the area," he wrote on Twitter.
Ankara says it is necessary to curb the power of the SDF due to its ties with Kurdish militants inside Turkey.
It also wants a "safe zone" on the Syrian side of the border where it could send back some of the 3.6 million refugees it hosts from the eight-year war.
President Donald Trump insisted the United States had not abandoned its Kurdish allies.
Trump was widely seen as giving a green light at the weekend, ordering the pullback of U.S. troops from the Turkey-Syrian border which had served as a buffer.
Russian President Vladimir Putin urged Erdogan to "think carefully" before the offensive, while the European Union demanded Turkey halt its military operation.
Iranian President Hassan Rouhani said that the Syrian military is the only power that can ensure security along the country's northern borders with Turkey.
"The solution to achieving security in Syria’s northern and Turkey's southern border region lies only in the presence of the Syrian military there,” President Rouhani said.
He said all sides involved needed to help set the stage for conditions that would allow the Syrian army’s presence in the region, adding Iran had conveyed this position during talks with Russia and Turkey in Ankara last month.
The Iranian president further security in the border region also required the withdrawal of American forces from the territory.
Rouhani further advised Kurdish forces in Syria to join forces with the Syrian military, stressing that Syria is their rightful homeland.
President Rouhani acknowledged Turkey’s legitimate concerns regarding security along its southern borders, but noted that "agreements made behind the scenes would not benefit the region.”
"We believe that a suitable path has to be chosen regarding this matter,” Rouhani said, adding, "We urge our friend Turkey and its government to pay more attention to such matters and reconsider the decision that has been made."
Rouhani said the Turkish incursion was problematic at a time when the region needed calm and Syrian refugees sought to resettle in the country.
"Today, our main problem does not lie in northern Syria and east of the Euphrates River, but the foremost problem lies in the Idlib region where all the terrorists have gathered," the president said.
The Turkish government played a major role in supporting various militant groups that sought to topple Syrian President Bashar al-Assad eight years ago.
Kurdish authorities on Wednesday announced a general mobilization, urging all civilians to "head to the border with Turkey... to resist during this delicate historical moment".
Shortly after fighting started, Anadolu news agency said two shells hit the Turkish town of Ceynalipinar and six rockets hit Nusaybin.
"Both Turkish and Kurdish forces have a track record of carrying out indiscriminate attacks in Syria that have killed scores of civilians," warned Amnesty International's Middle East research director Lynn Maalouf.
"This must not be allowed to happen again," she added.
Kurdish leaders said they would hold their erstwhile U.S. ally and the whole international community responsible for any "humanitarian catastrophe".
In Ras al-Ain, Kurdish-led security forces set up checkpoints and stockpiled tires to set alight to blur the vision of Turkish military pilots, an AFP correspondent reported.
Ras al-Ain was one of the places from which U.S. troops withdrew on Monday. "We will not leave this land," said Kawa Sleem, a 32-year-old Ras al-Ain resident.
"War has been chasing us for years, and everyday Erdogan threatens us with a new attack," he added.
It was expected that Ras al-Ain and Tal Abyad -- both with Arab-majority populations -- would be the focus of the first aggression.
Kurdish forces have dug trenches and tunnels in both areas, covering streets with metal canopies to block the cameras of Turkish drones, AFP said.
Russian Foreign Minister Sergei Lavrov said that Iraqi Kurdish leaders he met earlier this week had voiced deep concern about the mixed signals from Trump.
"They are extremely alarmed that such a lightweight treatment of this extremely delicate subject could ignite the entire region," Lavrov said.
Since 2015, Russia has been the main military backer of the Syrian government, which has called on the Kurds to accept the restoration of central government control.
The Kurds called on Moscow on Wednesday to facilitate dialogue with Damascus.
They have warned that a Turkish offensive would reverse the military gains achieved against Daesh and allow the jihadist group's surviving leaders to come out of hiding.
Turkey said it would not allow a resurgence of Daesh, but called on European countries to repatriate Takfiri prisoners being held in Kurdish detention centers.