U.S. President Donald Trump on Wednesday described Turkey's incursion into northern Syria as a "bad idea."

Trump -- who pulled out US troops from the area in what was interpreted as a green light for Turkey to assault Kurdish militias previously allied with the United States -- insisted that Washington "does not endorse this attack."

In launching an offensive against Kurdish forces in Syria, Turkey is risking a new low in relations with the United States including potentially painful sanctions, even if President Donald Trump may prove sympathetic.

The Netherlands summoned Turkey's ambassador on Wednesday to condemn Ankara assault on Kurdish forces in northern Syria, warning that it risked a resurgence of the Islamic State group.

Calm prevailed in Iraq on Wednesday after a week of anti-government protests left more than 100 dead, prompting the United States to call on the country's government to exercise "maximum restraint."

The U.N. Security Council will hold an emergency meeting Thursday to discuss Turkey's military offensive in northern Syria, diplomats said Wednesday.

Turkey "is willingly risking further destabilizing the region and a resurgence of IS" (Islamic State) by attacking northeastern Syria, German Foreign Minister Heiko Maas said Wednesday. 

NATO chief Jens Stoltenberg on Wednesday urged Turkey to show "restraint" in its operation against Kurdish forces in Syria, warning that the fight against the Islamic State group should not be put at risk.

The head of Saudi Aramco hit out Wednesday at the lack of global resolve to stop attacks on more oil installations, one month after strikes on two of its facilities.

The Turkish military operation launched on Wednesday against Kurdish militia fighters in Syria is Ankara's third offensive in the war-torn country.

France "strongly condemns" Turkey's offensive in northeast Syria, European Affairs minister Amelie de Montchalin said Wednesday, within minutes of Ankara launching cross-border strikes.