Washington said its troops in northern Syria came under fire from NATO ally Turkey on Friday, as Ankara ramps up offensive against Syrian Kurds.
An explosion was reported later Friday in northern Syria near an outpost where U.S. troops are located, but none of the Americans were hurt, according to a U.S. official and a Syria war monitor.
It was unclear whether it was from artillery or an airstrike, and it was the first time a coalition base was in the line of fire since Turkey's offensive began on Wednesday.
Turkey said the U.S. was not targeted and its forces were returning fire after being targeted by Kurdish fighters about half a mile from the U.S. outpost. The Turkish defense ministry said the Turkish army took every precaution to ensure no damage to the U.S. post. It says it stopped striking the Kurdish target after communicating with the U.S.
Navy Capt. Brook DeWalt, a Pentagon spokesman, said the artillery explosion came within a few hundred meters of the area where U.S. forces were, adding that Turkey must avoid actions that could result in immediate defensive action by the U.S.
U.S. officials said a number of American troops left the post outside the Kurdish-held town of Kobani after it came under fire. The officials say a large base in the town has not been affected by the shelling.
The officials say they expect the evacuation to be temporary.
Syrian Observatory Director Rami Abdurrahman also said there was intense Turkish shelling of Kobani Friday. He said projectiles landed near the coalition base on a hill at the edge of town.
The Kurdish news agency Hawar reported that it was an artillery shell. Both the Observatory and Hawar said U.S. warplanes flew over the base immediately after the incident.
Turkey's foreign ministry later said that the Turkish military operation in Syria will proceed "with determination," despite U.S. warnings of possible sanctions.
In a statement late Friday, ministry spokesman Hami Aksoy said Turkey had informed the U.S. at all levels of its operation against Syrian Kurdish fighters.
"Turkey is fighting terrorist organizations that are a threat to its national security and this fight will be continued with determination," Aksoy said.
Responding to the threat of U.S. sanctions, Aksoy said: "No one should doubt that we will respond in kind against each step to the full extent of reciprocity."
At the White House, Treasury Secretary Steven Mnuchin put Turkey on notice that it could face "powerful sanctions" for its military incursion, and that the U.S. will "shut down the Turkish economy" if Ankara goes too far.
Earlier, Turkey said it captured more Kurdish-held villages in the border region, while a hospital in a Syrian town was abandoned and a camp of 4,000 displaced residents about 12 kilometers (7 miles) from the frontier was evacuated after artillery shells landed nearby.
Kurdish fighters waged intense battles against advancing Turkish troops that sought to take control of two major towns along the Turkish-Syrian border, a war monitor said.
Reflecting international fears that Turkey's offensive could revive the Islamic State, two car bombs exploded outside a restaurant in the Kurdish-controlled urban center of Qamishli, killing three people, and the extremists claimed responsibility. The city also was heavily shelled by Turkish forces.
UN diplomats say Russia and China have blocked the Security Council from adopting a U.S.-drafted statement calling on Turkey to go through diplomatic channels rather than take military action against the Kurds in northeast Syria.
The diplomats, speaking on condition of anonymity, say Moscow and Beijing raised objections to the statement before a deadline Friday afternoon.
The objection by Syrian ally Russia, backed by its close ally China, was not surprising.
Russia's UN Ambassador Vassily Nebenzia told reporters after a closed Security Council meeting Thursday that any council statement needs to take into account other aspects of the Syrian crisis, not just the Turkish operation — and should demand the immediate termination of "the illegal military presence" in the country.
The UN estimated the number of displaced at 100,000 since Wednesday, saying that markets, schools and clinics also were closed. Aid agencies have warned of a humanitarian crisis, with nearly a half-million people at risk in northeastern Syria.
U.S. President Donald Trump pulled troops back from the border this week, saying he wanted American forces out of harm's way.
Syrian Kurdish officials said Turkish shelling has hit a prison holding Islamic State militants in northeastern Syria.
A video shared by the officials Friday shows a shell landing in the courtyard of what appears to be a prison facility in the city of Qamishli. Seconds later, a handful of men open doors and seem to be trying to leave.
An official with the mostly Kurdish Syrian Democratic Forces says some of the men in the video are security guards seeking to contain the escape and regain control of the prisoners. The official spoke on condition of anonymity because he wasn't authorized to brief the media.
It was not possible to verify the attempted escape. But chaos and the ongoing assault have raised fears that the Turkish offensive on Kurdish-held northeastern Syria may undermine the security of over two dozen facilities where 10,000 ISIS militants are held. There are 2,000 foreigners among them.
The Kurdish officials said Turkish shells fell near another prison facility on Friday and Wednesday in Qamishli, which is only 2 miles (3 kilometers) from the Turkish border.
Turkish President Recep Tayyip Erdogan said his county "will not take a step back" from its offensive against Syrian Kurdish militants it sees as a national security threat, defying serious warnings from the United States and other Western nations.
Erdogan said he had given ample time to Trump to stop supporting and arming the Kurdish fighters, which form the backbone of the Syrian Democratic Forces fighting the Islamic State group.
Turkey had been threatening an offensive for months, saying it would not allow a de facto state run by the Kurdish forces, which has links to an outlawed group considered a terror organization by Turkey and the United States.
Erdogan said Turkey "will continue this fight" until the Kurdish militants are pushed back 32 kilometers from the Turkish border.
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