Turkish President Recep Tayyip Erdoğan launched a military operation in the near future against the Kurdish people's protection units east of the Euphrates River in Syria, defying Washington's rejection of any military action against its Syrian Kurdish allies.

In a speech on Tuesday at an annual conference of Turkish ambassadors in Ankara, Erdogan said his country was ready to use force to protect its national interests.

He added that the elimination of what he called the "terrorist entity" in the north-east of Syria is a priority of his country, considering that this entity (Kurdish Syrian) grows like cancer cells and threatens the security of Turkey.

He added that his country will take very soon steps related to the phase of operations initiated by Operation Euphrates Shield in Syria since August 2016 in cooperation with the Syrian opposition factions, and was able to take out the Islamic State Organization from the Syrian towns in the countryside of Aleppo North.

The Turkish president said that Turkey would later pay a heavy price if it did not do so in northern Syria, adding that Ankara was waiting for the United States to take a step worthy of a real strategic ally.

The comments come as Turkish-US negotiations falter over the establishment of a safe zone in northern Syria, which Ankara says will allow the return of hundreds of thousands of refugees to Syria and reduce threats to Turkey.

Turkey wants the safe area to be 30 to 40 kilometers deep inside Syrian territory, stretching from eastern Euphrates to the eastern outskirts of Aleppo to the Iraqi border. The area is now under the control of the so-called Syrian Democratic Forces, whose Kurdish units are the backbone.

While Erdogan was looming in Ankara for military action against Kurdish units in Syria, US Defense Secretary Mark Esber said from Tokyo that any Turkish military operation in the eastern Euphrates region of northern Syria would be unacceptable and that Washington would block it.

The Turkish president outlined the objectives of a possible new military operation in Syria, in addition to eliminating the "terrorist entity" formed by Syrian Kurdish units: speeding up the process of returning Syrian migrants to their country.

Erdogan has repeatedly threatened a military operation against Kurdish units, which Ankara considers an extension of the PKK, and controls an area that includes parts of the provinces of Aleppo, Hasaka and Raqqa, and spread in this region hundreds of American soldiers.

The threat appeared this time, and Kurdish leader Aldar Khalil told Agence France-Presse that Erdogan was serious and would attack at the first opportunity.

Part of the Russian S-400 missile cargo unloaded at an air base in Ankara (European)

Relationship with Washington
In his speech today in Ankara, the Turkish president called on the United States to extradite his country to the leaders of the Gulen organization, which Ankara calls terrorist, and to take responsibility for the attempted coup three years ago and stop arming the Kurdish units.

Erdogan also spoke about the repercussions of his country's acquisition of Russian S-400 missiles on its relations with the United States and NATO.

"It is wrong to question Turkey's commitment to NATO over the Russian missile deal," he said, adding that there was no concrete evidence that the S-400 would damage US F-35s or NATO.

He described the acquisition of Russian anti-aircraft missiles as a non-strategic trade decision, saying that US President Donald Trump would not allow the Turkish-US relations to be in dispute over Russian missiles.

Last month Turkey received the first batch of the S-400 missile system, and the system is due to be fully deployed in April next year.

Washington responded to the deal by excluding Turkey from its F-35 production program and has also sanctioned Ankara but has yet to implement its threats.