WASHINGTON - US President Donald Trump said on Wednesday that Turkey had informed the United States that the cease-fire in Syria would be "permanent," and he ordered US sanctions on Turkey over its offensive in northern Syria to be lifted.

Trump announced at the White House that the Turkish government had informed the United States earlier in the day that Turkish forces would stop their offensive in Syria, keeping the cease-fire "permanent."

"I do believe it will be permanent," Trump said in the remarks.

"I have therefore instructed the Secretary of the Treasury to lift all sanctions imposed on Oct 14," he said, adding that Washington reserves the right to re-impose sanctions against Ankara if it fails to honor its obligations.

"The sanctions will be lifted unless something happens that we are not happy with," he noted.

Earlier this month, the Trump administration imposed a series of sanctions on Turkey over its military operations in Syria, including sanctions against several Turkish government departments and their heads, extra tariffs on steel imports from the country, and the suspension of negotiation on US-Turkey trade deal.

Trump's remarks came just one day after Russia and Turkey's joint agreement on establishing a safe zone in northern Syria on the condition that Kurdish forces withdraw.

According to the document, the Kurdish forces have to withdraw within 150 hours to the depth of 30 km from the Turkish-Syrian border on the Syrian side. Russian and Turkish forces will then start joint patrols in the area of Operation Peace Spring in northern Syria to a depth of 10 km, excluding Qamishli city.

"Other countries have stepped forward, they want to help, and we think that's great," Trump said.