Turkey pledged on Monday to press ahead with plans to target a Kurdish militia in northern Syria, brushing off what it said were American efforts to stymie Turkish military operations east of the Euphrates.
President Tayyip Erdogan said last week that Turkey would launch a new operation within days against the US-backed Syrian Kurdish YPG militia in northern Syria. The Pentagon expressed grave concern and said unilateral military action there by any party would be "unacceptable".
Relations between the two NATO allies have long been strained by Syria policy. The United States has backed the YPG against Daesh fighters. Ankara, however, sees the YPG as terrorists tied to PKK militants who have fought an insurgency in southeast Turkey for 34 years.
Interior Minister Suleyman Soylu said Washington had tried to hold Turkey back during two operations in Syria in the last two years against Daesh and the YPG, which controls swathes of Syria's northern border region.
"The United States thought it could deter us with the men it has nurtured," he said during a visit to Pakistan, Anadolu Agency reported, adding:
Now, they will try to hold us back east of the Euphrates. Turkey did not, and will not, allow that.
Turkey has not yet launched an operation east of the Euphrates but has kept up regular air strikes against Kurdistan Workers Party (PKK) militants based in Iraq's mountains.
Baghdad summoned Turkey's ambassador to Iraq on Friday after Ankara said it killed eight PKK fighters. But Turkish warplanes have since carried out further strikes.
On Monday, Turkey's defence ministry said air strikes on Sunday targeted northern Iraq's Gara and Hakurk areas and "neutralised" seven militants preparing to attack Turkish bases.
Erdogan has said Turkish forces will enter the Syrian town of Manbij, west of the Euphrates, if the United States does not remove YPG fighters there and will also target the eastern side, where the YPG controls an area stretching more than 400 km (250 miles) along the border towards Iraq.
On Sunday he vowed again to maintain attacks on militants.
"We are always in the heads of the terrorists. We are burying them in the ditches they dig. We will continue to bury them," he said in a rally in Istanbul.
"Terrorists will cease to be an affliction for my nation," he said. "Together with God's permission we are making those who attack our homeland and borders pay the price."
The United States has set up observation posts on the Syrian border, saying they will deter security threats against Turkey coming from Syria. It has warned Turkey against a new incursion.