Donald Trump has described Kurds as "no angels" as he attempted to defend his decision to allow Turkey's offensive in Syria.

The comments from the president — who also said it was "fine" for Russia to assist Assad regime in the conflict — come despite Kurdish forces being longstanding allies of the US who played a key role in the defeat of Isis.

He also claimed imposing US sanctions on Turkey would be better than fighting in the region.

"All American soldiers are away from the site. Syria and Turkey can fight... They’ve got a lot of sand over there... There’s a lot of sand that they can play with,” Mr Trump said in the White House.

"They are no angels, by the way," Mr Trump continued, referring to a group who have been bombarded since the US pulled troops from northern Syria, allowing the Turkish offensive.

"If Turkey goes into Syria it is between Turkey and Syria. It’s not our problem," he said.

In pictures: Fighting between Kurds and Isis intensifies in Kobani Show all 30 1 /30 In pictures: Fighting between Kurds and Isis intensifies in Kobani In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani An explosion rocks Syrian city of Kobani during a reported suicide car bomb attack by the militants of Isis group on a People's Protection Unit (YPG) position in the city center of Kobani, as seen from the outskirts of Suruc, on the Turkey-Syria border In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani An explosion rocks the Syrian city of Kobani during a reported suicide car bomb attack by Isis Getty In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani An explosion in the Syrian city of Kobani set off as fighting continues Getty Images In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Heavy smoke rises following an air strike by the US-led coalition aircraft in Kobani Getty Images In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani An unidentified armed man takes position near a building in the Syrian town of Kobani, as seen from near the Mursitpinar border crossing on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Kurdish fighters walk to their positions in Kobani In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Residents of Kobani walk in the streets of the besieged town, as seen from near the Mursitpinar border crossing on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani People's Protection Unit (YPG) fighters walk in the Syrian town of Kobani, as seen from near the Mursitpinar border crossing on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani People watch the Syrian town of Kobani from near the Mursitpinar border crossing, on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani A Turkish soldier stands on a top of a tank as he watches the Syrian town of Kobani from near the Mursitpinar border crossing, on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Smoke rises from the Syrian town of Kobani, seen from near the Mursitpinar border crossing on the Turkish-Syrian border in the southeastern town of Suruc. Kurdish forces defending Kobani urged a U.S.-led coalition to escalate air strikes on Isis fighters who tightened their grip on the Syrian town at the border with Turkey. A group that monitors the Syrian civil war said the Kurdish forces faced inevitable defeat in Kobani if Turkey did not open its border to let through arms, something Ankara has appeared reluctant to do In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Newly arrived People's Protection Unit (YPG) fighters walk in a line in the Syrian town of Kobani, seen from near the Mursitpinar border crossing on the Turkish-Syrian border In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Heavy smoke rises from the Syrian town of Kobani, seen from near the Mursitpinar border crossing on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Kurdish women mourn at the grave of a relative, who was a Kurdish fighter killed in fighting with the militants of the Islamic State group in Kobani, and was buried at a cemetery in Suruc In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Turkish army tanks mechanized units take position on top of a hill near Mursitpinar border crossing in the southeastern Turkish town of Suruc in Sanliurfa province In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Smoke rises after an US-led air strike in the Syrian town of Kobani. The air strikes pushed Isis fighters back to the edges of the Syrian Kurdish border town of Kobani, which they had appeared set to seize after a three-week assault, local officials said In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani A huge plume of smoke rises after an airstrike in eastern Kobani, Syria, behind a hilltop where militants with the Islamic State group had raised their flag on Monday AP In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Turkish Kurds watch as airstrikes hit Kobani AP In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Smoke rises from the Syrian town of Kobani as Turkish army tanks take position on the Turkish side of the border Reuters In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Military aircraft flies over the Turkey-Syria border as it nears targets in Kobani In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Smoke rises after a US-led air strike in the Syrian town of Kobani Reuters In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Turkish Kurds, on the Turkey-Syria border, watch over the border at the intensified fighting between Isis and Kurdish forces AP In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Smoke rises during airstrikes on the Syrian town of Ain al-Arab, known as Kobani by the Kurds Getty In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani A huge plume of smoke rises after an airstrike outside west Kobani, Syria AP In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani A militant with the Isis group walks in the town of Kobani In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Militants with the Isis group, bottom, along with a machine gun-fitted pick up truck, partially seen bottom right, hold positions in Kobani, during intensified fighting with Syrian Kurds In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani People watch smoke rising from the Syrian town of Ain al-Arab, known as Kobani by the Kurds, after an air strike Getty In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Smoke rises from a strike at an area of a mosque that destroyed its minaret, in Kobani during heavy fighting between militants with the Isis group and Syrian Kurds In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani Militants with Isis hold positions in Kobani, Syria, during intensified fighting with Syrian Kurds AP In pictures: Fighting between Kurds and Isis intensifies in Kobani Kobani A partial view of Kobani with a mosque's minaret

During his remarks, Mr Trump welcomed the addition of further international involvement, saying that he is fine with Russia helping Syrian leader Bashar al Assad in fighting against Isis and other adversaries.

Mr Trump has been widely criticised for his decision remove US troops from northern Syria, which has led to a military assault on Kurdish forces who lost more than 10,000 soldiers fighting alongside the US against Isis.

"The Kurds are much safer right now, but the Kurds know how to fight," he said, suggesting that the Kurds were better at fighting when allied with the United States than when they were not. "They fought with us. We paid a lot of money to fight with them but that's ok."

The backlash against Mr Trump over the issue has pushed him to impose fresh sanctions on Turkey, and to halt trade negotiations with the country.

In addition, Mr Trump has called on Turkey to impose a cease fire in the area, and is sending vice president Mike Pence to the region to help negotiate that measure on Wednesday. Turkey, however, has indicated that it does not want to impose a cease fire.

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Joining Mr Pence is secretary of State Mike Pompeo, who said during an interview with Fox News on Wednesday morning that Mr Trump wanted those two to begin negotiations to ensure the Turkish government understands the US is taking the issue seriously.