The US on Wednesday warned Turkey against launching an operation targeting Kurdish militias in northern Syria, saying such action would be "unacceptable."

"Unilateral military action into northeast Syria by any party, particularly as US personnel may be present or in the vicinity, is of grave concern," said Commander Sean Robertson, a spokesman for the Pentagon.

Robertson said Washington was committed to Turkish border security, but noted that the US-backed Syrian Democratic Forces (SDF) led by the Kurdish People's Protection Units (YPG) remained a "committed partner" in the fight against the "Islamic State" (IS) militant group.

"We should not and cannot allow ISIS to breathe at this critical point or we will jeopardize the significant gains we have made alongside our coalition partners and risk allowing ISIS to resurge," Robertson said, referring to the militant group by an alternative acronym.

But Turkey considers the YPG an extension of the terrorist-designated Kurdistan Workers' Party (PKK) and views its consolidation of territory in parts of Syria as a threat.

Read more: Is the 'Islamic State' making a comeback in Iraq?

Watch video 12:04 Share World Stories - Syria - Final Chapter in Terror War? Send Facebook google+ Whatsapp Tumblr linkedin stumble Digg reddit Newsvine Permalink https://p.dw.com/p/36TPk World Stories - Syria - Final Chapter in Terror War?

Operation 'in a few days'

The Pentagon's remarks came hours after Turkish President Recep Tayyip Erdogan said Turkey would launch an offensive against the YPG in the near future.

"We will start the operation to clear the east of the Euphrates from separatist terrorists in a few days," Erdogan said during a speech at a defense industry summit in Turkey. "Our target is never US soldiers."

While Turkey has attacked Kurdish fighters in Syria, it has hesitated to launch an offensive east of the Euphrates, where the US has troops deployed in the fight against IS. The Turkish government has been frustrated with the US concerning a deal for the area.

"The step will allow for the path to a political solution to be opened and for healthier cooperation," Erdogan said.

Read more: Who are the Kurds?

Every evening, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.

Who's fighting in the Syria conflict? War with no end Syria has been engulfed in a devastating civil war since 2011 after Syrian President Bashar Assad lost control over large parts of the country to multiple revolutionary groups. The conflict has since drawn in foreign powers and brought misery and death to Syrians.

Who's fighting in the Syria conflict? The dictator Syria's army, officially known as the Syrian Arab Army (SAA), is loyal to Syrian President Bashar al-Assad and is fighting to restore the president's rule over the entire country. The SAA has been fighting alongside a number of pro-Assad militias such as the National Defense Force and has cooperated with military advisors from Russia and Iran, which back Assad.

Who's fighting in the Syria conflict? The northern watchman Turkey, which is also part of the US-led coalition against IS, has actively supported rebels opposed to Assad. It has a tense relationship with its American allies over US cooperation with Kurdish fighters, who Ankara says are linked to the Kurdistan Workers' Party (PKK) fighting in Turkey. Turkey has launched multiple military offensives targeting Kurdish militias.

Who's fighting in the Syria conflict? The eastern guardian The Kremlin has proven to be a powerful friend to Assad. Russian air power and ground troops officially joined the fight in September 2015 after years of supplying the Syrian army. Moscow has come under fire from the international community for the high number of civilian casualties during its airstrikes. However, Russia's intervention turned the tide in war in favor of Assad.

Who's fighting in the Syria conflict? The western allies A US-led coalition of more than 50 countries, including Germany, began targeting IS and other terrorist targets with airstrikes in late 2014. The anti-IS coalition has dealt major setbacks to the militant group. The US has more than a thousand special forces in the country backing the Syrian Democratic Forces.

Who's fighting in the Syria conflict? The rebels The Free Syrian Army grew out of protests against the Assad regime that eventually turned violent. Along with other non-jihadist rebel groups, it seeks the ouster of President Assad and democratic elections. After suffering a number of defeats, many of its members defected to hardline militant groups. It garnered some support from the US and Turkey, but its strength has been greatly diminished.

Who's fighting in the Syria conflict? The resistance Fighting between Syrian Kurds and Islamists has become its own conflict. The US-led coalition against the "Islamic State" has backed the Syrian Democratic Forces, an alliance of Kurdish and Arab militias. The Kurdish YPG militia is the main component of the SDF. The Kurds have had a tacit understanding with Assad.

Who's fighting in the Syria conflict? The new jihadists "Islamic State" (IS) took advantage of regional chaos to capture vast swathes of territory in Iraq and Syria in 2014. Seeking to establish its own "caliphate," IS has become infamous for its fundamentalist brand of Islam and its mass atrocities. IS is on the brink of defeat after the US and Russia led separate military campaigns against the militant group.

Who's fighting in the Syria conflict? The old jihadists IS is not the only terrorist group that has ravaged Syria. A number of jihadist militant groups are fighting in the conflict, warring against various rebel factions and the Assad regime. One of the main jihadist factions is Hay'at Tahrir al-Sham, which controls most of Idlib province and has ties with al-Qaeda.

Who's fighting in the Syria conflict? The Persian shadow Iran has supported Syria, its only Arab ally, for decades. Eager to maintain its ally, Tehran has provided Damascus with strategic assistance, military training and ground troops when the conflict emerged in 2011. The Iran-backed Lebanese Shiite militant group Hezbollah also supports the Assad regime, fighting alongside Iranian forces and paramilitary groups in the country. Author: Elizabeth Schumacher, Alexander Pearson



ls/jm (AFP, Reuters, dpa)