On Tuesday, Turkish officials told Reuters that the military had struck the Syrian-Iraqi border to prevent Kurdish forces using the route to reinforce the region, though details of the strikes were hazy.
The two authors condemned Trump's "abrupt" decision to withdraw US troops from northeastern Syria-where they were supporting America's Kurdish-led allies-in the face of an imminent Turkish assault on the area.
President Donald Trump meanwhile denied the Kurds had been abandoned by the USA pullback, praising Turkey as a trade partner and North Atlantic Treaty Organisation ally in a softening of his tone hours after threatening Ankara's economy if it acted "off limits" in Syria.
The primary motive for Turkey's military operation is to clear the Kurdish militias from its border region, such as the People's Protection Units (YPG) in Syria which is now entrenched east of the Euphrates River in particular and which Turkey sees as a national security threat, as well as the establishment of a safe zone in the north-east of the country.
In its more than 30-year terror campaign against Turkey, the PKK - listed as a terrorist organization by Turkey, the US and the European Union - has been responsible for the deaths of some 40,000 people, including women, children and infants.
Al Jazeera's Charles Stratford, reporting from Akcakale along Turkey's border with Syria, said: "All evidence suggests that the operation could be imminent". "Kurds in Syria. should support the Syrian army", state news agency IRNA quoted Rouhani as saying.
"Naturally our preparations are along the length of the border with Turkey, and our forces are in a state of readiness", Mr Bali told Reuters. The area is about 620 kilometres northwest of Tehran.
Trump's decision late Sunday to move US forces prompted an immediate backlash from USA lawmakers, some of whom called it a betrayal of the Syrian Kurds, viewed by many in Washington as the most dependable ally in the fight to destroy the IS caliphate.
On Monday, Trump said that getting the United States out of military conflicts was the reason he was elected president.
US senators from both parties on Tuesday demanded a senators-only briefing from the Trump administration over its decision to withdraw USA troops from northern Syria.
President Tayyip Erdogan's communications director said Turkey had no ambition in northeastern Syria except to neutralise then threat against Turkish citizens and to liberate the local people from what he called "the yoke of armed thugs".More news: U.S. Air Force F-16 fighter jet crashes in Germany
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"Where Turkey's security is concerned, we determine our own path but we set our own limits", Oktay said.
The statement said the mobilization would last for three days. The US has about 1,000 troops in Syria.
Trump's warning on Turkey's economy on Monday appeared aimed at placating critics who accused him of abandoning the Syrian Kurds. Lavrov said during a visit to Kazakhstan on Wednesday that the US first propped up the Syrian Kurdish "quasi state" in northeastern Syria and is now withdrawing its support. "As before, this is the only way to achieve stability", Lavrov said at a news conference in Kazakhstan.
"The same man who is a terrorist if he's in Turkey, he's a member of the PKK".
"We are helping the Kurds financially/weapons!", he added.
YPG fighters could either defect or Ankara would have to "stop them from disrupting our counter-Islamic State efforts", he wrote.
Earlier on Wednesday, ISIS militants targeted a post of the Kurdish-led Syrian Democratic Forces in the northern Syrian city of Raqqa, which was once the de facto ISIS capital at the height of the militants' power in the region.
The attack comes as Turkey is expected to launch an offensive against the Kurdish fighters in northeastern Syria.
Trump's decision effectively provides Turkish troops with a green light to attack US-backed Kurdish forces, though Trump threatened to punish Turkey economically if it does "anything outside of what we think is humane".
Erdogan says Turkey and the United States are working separately on plans to repatriate foreign fighters held in Kurdish prisons. There was no immediate word on casualties.
Raqqa is being Silently Slaughtered, an activist collective, reported an exchange of fire and a blast.
The Syrian Observatory for Human Rights said the Raqqa attack involved two ISIS fighters who engaged in a shootout before blowing themselves up.