Syrian Kurds, considered to be an American ally in the region, did not help the US in fighting against the ISIS, President Donald Trump has said, defending his decision to pull out American forces paving way for Turkey to launch a military operation to invade northeastern Syria.

"The Kurds are fighting for their land, just so you understand. They're fighting for their land. As somebody wrote in a very, very powerful article today, they didn't help us in the Second World War. They didn't help us with Normandy, as an example. They mentioned the names of different battles. They weren't there. But they're there to help us with their land, and that's a different thing," Trump told reporters at the White House on Wednesday.

Turkey has launched a broad assault on Kurdish-controlled areas in northeastern Syria, with intensive bombardment paving the way for a ground offensive.

The operation was possible after the White House announced late Sunday that Turkey would soon carry out a military operation in northern Syria and that US troops will no longer be “in the immediate area”.

Trump said the US has spent tremendous amount of money on helping the Kurds in terms of ammunition, weapons and pay.

"With all of that being said, we like the Kurds. Now, you have different factions in there. Again, you have PKK. That's a different faction, and they worked with us. It's a rough group, but they worked with us,” he said.

“But we've spent a tremendous--and they're fighting for their land. So, when you say they're fighting with us, yes, but they're fighting for the land,” Trump said.

Reiterating that it is time to bring US soldiers back home, Trump said that there are no American troops in the area where Turks have started invading Northern Syria.

“We've been talking to Turkey for three years. They been wanting to do this for many years, as you know. They been fighting each other for centuries. They been fighting each other for hundreds of years. This has been going on,” he said.

Trump said the US was forced into this battle and its presence in the area was supposed to be for a 30-day period.

"But it has been there for many years. It's time to get speaking to both sides, we've told President Erdogan how we feel, but we are speaking to both sides and we are seeing what can be made out of a situation,” he said.

Asserting that the US is getting out of the endless wars, Trump said that his administration has to do it.

"Eventually, somebody was going to have to make the decision,” Trump said, adding that he is getting a lot of praise for the decision.