WASHINGTON – President Donald Trump on Friday defended a U.S.-brokered halt to Turkey's military assault in Syria and made a puzzling assertion that the U.S. had "taken control" of oil fields in the region, even as fighting continued near the Syria-Turkey border.

"I just spoke to President (Recep Tayyip) Erdogan of Turkey. We're doing very, very well with Turkey," Trump said during an unrelated event at the White House. Turkey is "back to the full pause" on their military operation targeting Kurdish forces in northern Syria, Trump said.

The Kurds "are very happy about the way things are going," Trump added. "We've taken control of the oil in the Middle East ... the oil that everybody was worried about."

The president did not explain what he meant by taking "control of the oil in the Middle East." But he was likely referring to oil fields in eastern Syria, which Kurdish forces gained control over amid the chaos of Syria's civil war.

The Turkish invasion – which began last week after Trump withdrew U.S. troops from northeast Syria – jeopardized the Kurds' hold on those oil fields, as Russia, Iran and other military forces vied to fill a power vacuum left by the U.S.

Trump's remarks came before a scathing new broadside on the president's Syria policy, delivered by one of his chief allies: Senate Majority Leader Mitch McConnell, R-Ky.

Trump's decision to withdraw U.S. troops from Syria has created "a strategic nightmare for our country," McConnell wrote in a Washington Post op-ed published Friday.

Even if the U.S.-brokered cease-fire holds, McConnell said, immense damage has already been done: the U.S. campaign against the Islamic State has suffered a major setback, the Assad regime and its Iranian backers have expanded their influence in Syria, and Russia has gained new leverage in the Middle East.

"As neo-isolationism rears its head on both the left and the right, we can expect to hear more talk of 'endless wars'," McConnell added, taking aim at one of Trump's oft-cited justifications for withdrawing U.S. forces. But "America’s wars will be 'endless' only if America refuses to win them."

McConnell's op-ed added new heft to the already weighty attacks on Trump's latest foreign policy move and the chaos it has unleased. It came after signs that the U.S.-Turkey deal for at temporary cease-fire – which Trump boasted would save "millions of lives" – might not hold.

Earlier on Friday, a conflict-monitoring group and Kurdish authorities reported ongoing fighting in Syria, despite the "cease-fire" that Vice President Mike Pence announced on Thursday after negotiations with Erdogan in Ankara.

The Britain-based Syrian Observatory for Human Rights reported fighting in villages near the northeastern Syrian city of Ras al-Ayn. The Observatory said at least five people were killed and 14 injured. The Rojava Information Center, an independent media organization staffed by volunteers, said its activists on the ground also reported advances by Turkey-backed forces on two villages near Ras al-Ayn.

Mustafa Bali, a spokesman for the Syrian Kurdish forces, said on Twitter that Turkish "air and artillery attacks" targeting "fighters, civilian settlements and the hospital" in Ras al-Ayn were still taking place despite the agreement to halt military activity.

Trump downplayed the reports and said Erdogan told him there had been "minor" clashes but they had stopped.

"Just spoke to President @RTErdogan of Turkey. He told me there was minor sniper and mortar fire that was quickly eliminated," Trump tweeted earlier on Friday. "He very much wants the ceasefire, or pause, to work. Likewise, the Kurds want it, and the ultimate solution, to happen."

Secretary of State Mike Pompeo said Friday that he was not sure who was involved in Friday's clashes but suggested it could be Turkish-backed paramilitary forces.

“You have irregular forces in the region," Pompeo told Politico in an interview Friday. "I don’t know precisely what this is, but our sense is, the political commitments that were made yesterday will end up being successful."

Pompeo said Kurdish forces, known as the SDF, had begun to withdraw from the region, "so the key elements of the cease-fire look to be taking effect.”

In Brussels for NATO meetings, Pompeo also said he had not seen Trump's comments about taking control of the oil, and he did not answer questions about how the U.S. could be controlling any Syrian oil fields if U.S. troops were withdrawing.

Under the deal, Turkey agreed to halt its assault in Syria for five days after a Thursday visit to Turkey by Pence and Pompeo. Turkey's government described the agreement as a "pause."

Critics said the deal left many questions unanswered – including the fate of the Kurds – and was too little, too late.

"The Trump administration just capitulated to all of Turkey’s original demands after a week of violence and deep harm to America’s credibility in the world," said Kelly Magsamen, who served as a national security and defense official in the Obama administration. "If this is their idea of successful diplomacy, then we better hold onto our wallets when it comes on to China, Russia, Iran and North Korea."

Even before Friday’s developments, lawmakers in both parties had denounced the U.S.-Turkey deal as a “sham” that sold out the Kurds and weakened America's global standing.

“It is far from a victory,” said Sen. Mitt Romney, R-Utah, who sits on the Senate Foreign Relations Committee. “Serious questions remain about how the decision was reached to precipitously withdraw from Syria, and why that decision was reached.”

Romney said the pause in Turkey’s assault “does not change the fact that America has abandoned an ally” and he blasted President Trump for speaking “cavalierly, even flippantly” as the Kurds have “suffered death and casualty, their homes have been burned, and their families have been torn apart."

Since 2014, a U.S.-led coalition, which relied heavily on Kurdish ground forces, has rolled back the gains made by ISIS militants in Iraq and Syria.

Turkey regards the Kurdish fighters as terrorists and warned Trump that it planned an offensive against them. Erdogan ordered an assault on the Kurds shortly after Trump announced the departure of U.S. troops from the Turkish-Syria border region.

Sen. Richard Blumenthal, D-Conn., said the Turkish offensive against Kurds is “on the cusp of genocide.” He and other lawmakers on the Senate Armed Services Committee received a classified briefing Thursday on Turkey’s incursion from Defense Secretary Mark Esper and Army Gen. Mark Milley, the chairman of the Joint Chiefs of Staff.

Blumenthal said he could not reveal the details of the military presentation but described the mood in the room as serious and solemn.

"My reaction was horror and shame," he said. "And the American people should at least hear the essential facts of what is happening there.”

A U.S. official who is not authorized to speak publicly agreed with Bluementhal’s characterization of “horror and shame.”

The official said the cease-fire is not holding, and predicted it would cause more confusion and deaths among the Kurds.

Trump has pushed back hard in response to his critics.

"We've had tremendous success I think over the last couple of days," he said at the White House Friday. "Little bit unconventional, little bit of hard love," he said, referring to sanctions he placed on some Turkish officials Monday.

"Sometimes you have to go through some pain before you get a good solution. But the Kurds are very happy about it. President Erdogan of Turkey is satisfied with it. And we are in a very strong position," he said.

Trump also seemed to suggest that the U.S. had gained control of detention camps holding Islamic State fighters.

"We have ISIS totally under guard," the president said.

He was referring to Islamic State fighters, captured by the Kurdish forces who had allied with the U.S. to defeat that terrorist group in Syria. Some ISIS supporters escaped after Turkey invaded Syria, as Kurdish fighters left the detention facilities to confront the new military threat from Turkey.

House Speaker Nancy Pelosi, D-Calif., said the House will vote next week on a Turkey sanctions bill that would hit Erdogan’s government much harder than the narrow economic penalties Trump imposed earlier this week.

“President Erdogan has given up nothing, and President Trump has given him everything,” Pelosi and Senate Democratic Leader Chuck Schumer said in a joint statement Thursday evening. “Next week, the House will pass a strong, bipartisan sanctions package to work to reverse the humanitarian disaster that President Trump unleashed in Syria.”

That bill would ban the sale of U.S. arms to Turkey for use in Syria and require the administration to investigate Erdogan's net worth and assets. It would also slap sanctions on senior Turkish officials involved in the decision to invade Syria and target certain Turkish financial institutions that U.S. lawmakers said were "involved in perpetuating President Erdogan’s corrupt practices."

USA TODAY/Ipsos poll:Can our friends trust the US as an ally? Most Americans say Trump's Syria move has hurt

Erdogan disputed Friday that his forces were not abiding by the pause.

"I don’t know where you’re getting your news from. According to the news I received from my defense minister, there is no question of clashes. These are all speculation, disinformation," he told reporters in Istanbul Friday, according to Turkey's official Anadolu news agency.

Erdogan also said he wouldn't forget a letter sent to him by Trump, which he described as lacking "political and diplomatic courtesy."

In the letter, Trump urges his Turkish counterpart not to be a "tough guy" over Syria. Erdogan received it before he launched an incursion across the border into Syria. A BBC report claimed Erdogan angrily threw the letter in the trash after reading it.

Cease-fire:Mike Pence announces that Turkey agreed to a five-day cease-fire in its Syria assault