Turkish President Recep Tayyip Erdogan is warning of an imminent attack on a U.S.-backed Syrian Kurdish militia.
"We have finished our preparations. The operation can start any time," Erdogan declared to supporters at a rally Monday.
Turkish forces are massed along the border with Syria's Idlib enclave, which is controlled by the YPG, a Kurdish militia Ankara accuses of being linked to an insurgency in Turkey.
Erdogan has repeatedly warned the YPG presence in Idlib would be ended. As the Turkish military continues to build up its forces in the region, its artillery bombarded the enclave during the weekend. There also reports reports of special forces carrying out cross-border operations against YPG targets.
The latest escalation in tensions was triggered by Washington's announcement it is working with the YPG to create a border force.
"America has acknowledged it is in the process of creating a terror army on our border," Erdogan said Monday, "What we have to do is nip this terror army in the bud."
Washington views the YPG as a key ally in Syria in the war against the Islamic State and has armed the group despite Ankara's objections. The dispute has severely strained relations between the NATO allies.
Turkey at odds with Russia
But the YPG is also supported by Moscow. Russian Foreign Minister Sergey Lavrov issued a carefully-worded warning to Ankara over its latest threats.
"As for the situation in Afrin [enclave] and Syria overall ... We are seeking full compliance with the cease-fire agreements," he said during news conference Monday.
Russia and Turkey, along with Iran, have been working together in Syria in what has been dubbed the "Astana process."
Lavrov reserved his strongest criticism for Washington, attacking its decision to create a border force with the YPG.
"The U.S. unilateral, ultimatum-like project, aimed at establishing an army in Syria, may create problems in relations between Turkey and [the] Kurds," the minister said.
Moscow has been seeking to exploit Ankara's growing dispute with Washington as Turkey deepens its ties with Russia. But the balancing act could face its greatest test over Ankara's threat to attack Afrin with Russian military units in the enclave. The units were deployed last year to de-escalate tensions between the militia and Turkish forces.
Meanwhile, analysts warn the Turkish army could be overstretched. "The Turkish army is in Iraq. in Syria it is in two different places, said Haldun Solmazturk, a former brigadier and veteran of cross-border operations who now heads the Ankara based 21st century Turkey Institute.
"It is like a bomb," he added. "The Turkish army is sitting on a bomb."
Any operation in Idlib could be further complicated. The Turkish air force would need Moscow's permission to enter Syrian airspace due to the presence of Russian anti-aircraft missiles.
Moscow allowed Ankara to carry out limited airstrikes last year when its forces entered Syria to remove IS militants on its border. But doubt remains whether Russia would be accommodating again.
"Americans will never abandon Syrian Kurds, nor will Russia, which is supportive of the Syrian Kurds within a certain status, no doubt," claimed analyst Solmazturk. "They are simply too important in the region to both sides. The YPG control around one-fifth of Syrian territory."
Moscow, much to Ankara's discomfort, has been pushing for the presence of the militia or its political wing, the YPD, in an ongoing peace process to resolve the Syrian civil war.
"When we see Syria we notice that there are differences of opinion, which carry the seeds of problems," said political columnist Semih Idiz of Al Monitor website. "Turkey is not all that easy [about] the way Russia is trying steer the Syrian situation."
Ankara fears marginalization
Last week, Ankara summoned the Russian ambassador to protest Moscow's failure to rein in Damascus' ongoing military operation against rebels forces in Idlib. Analysts warn there is a growing concern in Ankara it could be marginalized by Washington and Moscow.
"Ankara seems to have no role anymore in the remaining episodes in this drama of Syria, so squeezed out is the right way to put it," claimed former Senior Turkish diplomat Aydin Selcen who served widely in region.
Analysts suggest Ankara's latest threat against the Syrian Kurdish militia in Afrin could be a move to remind the United States and Russia it remains a powerful player, given its large army and long border with Syria.
Such a robust stance also plays well domestically. Columnist Idiz said Erdogan has a receptive audience at home, but his stance "may backfire because Turkey, more or less, has angered [the United States] on a whole number of levels."