US President Donald Trump said on Wednesday that Syrian Kurds did not "help us in Normandy" during World War II, defending his decision to allow Turkish attack in northern Syria.

After sharp criticism of the decision, according to his forces from the region, Trump responded that Kurdish forces "are fighting for their territory."

"As someone wrote in a very powerful article today, they did not help us in World War II, they did not help us in the Normandy, for example."

Trump is probably referring to an article in the conservative Web site Naunhol supporting the decision to withdraw US troops from northern Syria, opening the way for the Turkish operation.

"The Kurds are fighting for their land, and that's different," Bush said.

"We have spent a lot of money helping the Kurds in terms of ammunition, weapons and money. When we say that, it means we love the Kurds."

Brett McGurk, who served as US special envoy to the coalition against ISIS, has in the past denied Trump's assertions.

"The weapons provided were poor," McGurk said. "Almost all funding for stabilization came from the coalition."

It is noteworthy that Trump on Sunday ordered the withdrawal of troops from northeastern Syria, paving the way for the military operation launched by Turkey since Thursday to remove Kurdish fighters from its borders and "establish a safe area to enable Syrian refugees to return to their homeland."

Turkey regards Kurdish fighters as a terrorist group because of their links to the PKK, which has been waging a decades-long insurgency in southeast Turkey.

Turkish media reports said Turkish troops entered Syria from four points, two of them close to Tel Abyad and the other near Ras al-Ain, which lies farther east.

The SDF said Turkish air strikes killed at least five civilians and three of its fighters.

Thousands of residents fled from Ras al-Ain towards Hasakeh province, which is controlled by the Kurdish-dominated Syrian Democratic Forces.