U.S. defense officials have stepped up warnings to Ankara as casualty reports mount amid a cross-border military assault by Turkey on Kurdish-controlled areas of northeastern Syria.
With Ankara's forces pushing deeper into Syrian territory against Syrian Kurdish fighters and international calls mounting for Turkey to end the three-day operation, U.S. Defense Secretary Mark Esper said on October 11 that he and other U.S. officials had "urged them to stop this incursion," adding that several other NATO members had done the same.
He added that Washington had not "abandoned the Kurds."
Esper reportedly warned Turkish Defense Minister Hulusi Akar earlier on October 11 that the operation risked progress made in the fight against the militant group Islamic State (IS).
But Esper told reporters hours later in Washington, "I see no lessening with regards to their commitment, at this point in time."
Reports quoted the Pentagon as saying Turkey's actions "risk serious consequences."
The United Nations said that by October 11 the Turkish operation had already displaced an estimated 100,000 people.
It said water supplies to 400,000 people in the city of Hasakeh and surrounding areas had also been cut off.
Turkish soldiers seized seven villages around the towns of Ras al-Ain and Tel Abyad, according to the Syrian Observatory for Human Rights.
The Britain-based war monitor reported that seven more civilians were killed by Turkish air strikes and sniper fire in and around Tel Abyad, bringing to 17 the number of civilians killed since the start of the offensive on October 9.
It said 29 fighters of the Kurdish-led Syrian Democratic Forces (SDF) have also died, along with 17 pro-Turkish Syrian fighters.
Meanwhile, Turkey announced that one of its soldiers was killed and three others wounded.
And at least five people, including a baby, died in the shelling of Turkish border towns, officials in Turkey said.
Turkish Defense Minister Akar said a total of 342 "terrorists" had been killed in the incursion so far.
The country has defended the operation as a bid to create a 30-kilometer-deep "safety zone" along its border with Syria free of Kurdish fighters, whom Ankara considers terrorists.
Turkey says such a "safe zone" could also house up to 2 million of the 3.6 million Syrian refugees living in Turkey.
President Donald Trump ordered the withdrawal of U.S. troops out of the area ahead of the Turkish assault.
Critics, including key Republican allies of Trump, have accused the White House of insufficient regard for the Kurds.
The Kurdish People's Protection Units (YPG), which dominate the SDF in northeastern Syria, has been key a U.S. ally in defeating the Islamic State (IS) extremist group in the war-torn country.
"We have not abandoned the Kurds, let me be clear about that," Esper told reporters at the Pentagon. "Nobody green-lighted this operation by Turkey, just the opposite. We pushed back very hard at all levels for the Turks not to commence this operation."
International condemnation of the Turkish assault has been quick, amid concerns about a developing refugee crisis.
A spokesman for the World Food Program (WFP) said in Geneva that more than 70,000 people had already fled the violence.
Another major concern is the fate of thousands of suspected IS prisoners, including many foreign nationals, being guarded by Kurdish-led forces in the region.
During a visit to Turkmenistan on October 11, Russian President Vladimir Putin said the captured IS fighters could escape as a result of the Turkish military operation.
"There are zones located in the north of Syria where Islamic State militants are concentrated. They were guarded until now by Kurdish armed forces. Now the Turkish army is going in, the Kurds are abandoning these camps. They could just escape," Russian news agencies quoted Putin as saying.
In Istanbul, NATO Secretary-General Jens Stoltenberg expressed worry that the Turkish operation could "jeopardize" gains made against the IS group.
Stoltenberg spoke a joint news conference with Turkish Foreign Minister Mevlut Cavusoglu, who said Ankara expected “solidarity” from its NATO allies.
Erdogan has threatened to send some of the Syrian refugees it hosts to Europe if the Turkish offensive is described as an occupation.
EU Council President Donald Tusk on October 11 condemned the threat as attempted "blackmail."
"Turkey must understand that our main concern is that their actions may lead to another humanitarian catastrophe, which would be unacceptable," Tusk said.
The UN Security Council discussed the situation on October 10 at the request of Belgium, Britain, France, Germany, and Poland.
But the 15-memnber council failed to agree on a statement, with Europeans demanding a halt to military action and Syrian ally Russia calling for "restraint" and "direct dialogue" between Syria and Turkey.
Republicans in the U.S. House of Representatives have announced plans to introduce legislation to impose sanctions on Ankara for its actions in northern Syria, while Trump has offered to “mediate a deal between Turkey and the Kurds.”
The Syrian conflict began with a government crackdown on protesters in March 2011 and has since killed more than 400,000 people and displaced millions.
Russia, along with Iran, has backed the government of Syrian President Bashar al-Assad, while the United States and Turkey have supported differing rebel groups. The IS group also entered the fighting and was opposed by all other sides.