WASHINGTON - President Donald Trump said Wednesday that a "permanent" cease-fire had been established in northeastern Syria, declaring a major diplomatic victory for his administration even as Russian forces began moving into territory once controlled by the United States and its Syrian Kurdish allies.

The president said that Turkish officials pledged to end their offensive in Syria and that he had ordered the lifting of sanctions imposed on Turkey earlier this month.

"This was an outcome created by us, the United States, and nobody else, no other nation. Very simple," he said.

Speaking in the Diplomatic Reception Room at the White House, Trump couched the agreement as part of his commitment to "a different course" in the Middle East, ending "endless wars" for which he has blamed his predecessors.

"Let someone else fight over this long-bloodstained sand," he said.

Responding to those who he said had "scorned" him for abandoning the Kurds and capitulating to Turkish demands, Trump said that "now people are saying, 'Wow. What a great outcome. Congratulations.' "

But many of those critics, including both Republican and Democratic lawmakers, were far from congratulatory, charging that Trump had opened the door to a resurgence of the Islamic State and expanded control of the region by Russia and Iran, allies of Syrian President Bashar Assad.

Trump, who announced the withdrawal of all U.S. troops in Syria two weeks ago, confirmed that a residual American force would remain near oil fields in eastern Syria. That area is south of a line of control Turkey has drawn 20 miles inside Syria.

"We're going to be protecting it, and we'll be deciding what we're going to do with it in the future," he said. U.S. officials have said about 200 troops, out of a total of about 1,000, will remain, along with another 100-150 at a separate garrison in southern Syria near the Jordanian border.

Trump thanked Turkish President Recep Tayyip Erdogan, calling him "a man who loves his country" and said that Syrian Kurdish leader Gen. Mazloum Kobani Abdi had told him in a phone call that he was grateful for U.S. efforts.

In Twitter messages posted on Mazloum's behalf, spokesman Mustafa Bali confirmed that gratitude and said Trump "promised to maintain" a partnership with the Kurdish-led Syrian Democratic Forces. The SDF served as the main ground force in routing the Islamic State with U.S. weaponry and air cover, but Turkey considers it a terrorist organization.

Mazloum also held a videoconference with Russian Defense Minister Sergei Shoigu, posted online by Russian media.

Trump's announcement came at a hastily organized event at which he was flanked by Vice President Mike Pence, Secretary of State Mike Pompeo and national security adviser Robert O'Brien.

Trump sent the three on a whirlwind trip last week to Ankara after Turkey sent its troops across the border just days after a Trump-Erdogan telephone call. During a long afternoon of talks, they agreed to a deal in which Turkey was given a five-day window to "pause" its operations in a 75-mile border strip in Syria to allow the exodus of Syrian Kurdish fighters. More than 160,000 civilians also fled from Turkish-allied Syrian militias and Turkish military bombardment.

If the pause succeeded and the Kurdish fighters left, Erdogan agreed to a more permanent "halt" in the fighting. In exchange, the administration agreed to drop existing sanctions and what Trump had promised would be even harsher economic measures.

Many critics were just as dismissive of Wednesday's announced victory as they were of the deal.

Sen. Chris Van Hollen, D-Md., who last week, along with Sen. Lindsey Graham, R-S.C., and others, co-sponsored a bill to impose legislative sanctions on Turkey, said Trump's "celebration . . . represents his total surrender of American leadership and the treacherous betrayal of our Syrian Kurdish allies."

On Twitter, Sen. Marco Rubio, R-Fla., said, in an apparent reference to the limited geography of the U.S.-Turkey cease-fire deal, said that Erdogan "has NOT agreed to stop all military operations in Syria." Russia, which on Tuesday signed a deal with Turkey to take control of hundreds more miles of Syrian territory along the border, "is going to remove Kurdish forces" from that area, "including Kurdish cities," and "take control of five oil fields."

Others referred to the likelihood of an Islamic State resurgence as the Kurds look for new alliances and their U.S. mentors and protectors withdraw. Already, administration officials have reported "dozens" or more escapes from Kurdish-held prisons in Syria. Trump said that "a few got out - a small number, relatively speaking - and they've been largely recaptured."

Graham, a Trump ally who said last week that Erdogan should be treated like "the thug he is," stepped back from his sharp criticism, tweeting that "this cease-fire, if permanent, represents real progress." He stressed the importance of maintaining control of the Syrian oil fields.

A senior administration official said inducements offered to Erdogan this month not to invade - including a $100 million trade deal, resolution of a dispute over Turkish purchase of a Russian missile defense system and a White House visit in November - were likely to be back on the table. Trump said only that he and Erdogan "may be meeting in the very near future."

Under the agreement signed by Erdogan and Russian President Vladimir Putin in the Black Sea resort of Sochi, Kurdish fighters have until next week to withdraw from an area stretching from the Euphrates River to the Iraqi border.

If armed Kurdish units do not retreat, Kremlin spokesman Dmitry Peskov told Russian media, "that will have to be done by Syrian border guards and Russian military police. In that case, the Turkish army will roll over the remaining Kurdish units."

Russian military police began patrolling parts of northeast Syria on Wednesday under the agreement. Russia's Defense Ministry and local media reports said that a column of Russian military vehicles arrived in the city of Kobane, which until recently hosted a U.S. military base. The ministry said that Syrian government forces would also establish observation posts along the frontier.

Asked about the Russian role, a second senior administration official who also briefed reporters on the condition of anonymity, said,"I think we always watch the Russians warily wherever we are."

But, the official said, "the deal between Turkey and the Russians is something that's between them. We did not have any role in that."

"The reality is, the [Turkish] operation took place, there was fighting that broke out as a result, the president stepped in and negotiated . . . a temporary cease-fire that now appears to be permanent" and "helped save a lot of lives," the official said. "We think that's a victory."

In an apparent reference to Turkey and Russia, Trump said that "others have come out to help and we welcomed them to do so; others have come forward."

In Iraq, visiting U.S. Defense Secretary Mark Esper faced opposition from the government in Baghdad to U.S. plans to redeploy withdrawing troops to Iraqi territory. The Pentagon chief had said earlier this week that U.S. forces departing Syria would redeploy to western Iraq to continue fighting the Islamic State.

Iraqi Defense Minister Najah al-Shammari told the Associated Press that U.S. forces were only "transiting" through Iraqi territory and would depart within four weeks.

"The government has confirmed that it will not grant permission for U.S. forces retreating from Syrian territory to remain in Iraqi territory," Iraqi Prime Minister Adel Abdul Mahdi said in a statement after meeting Esper.

He said Iraq was "taking all international legal measures" over the deployment of U.S. troops.

Earlier in the day, the Russian Foreign Ministry said that the Syrian government should retain control the oil facilities in northeastern Syria.

The Kremlin also said Wednesday that the United States had betrayed and abandoned the Kurds in Syria.

"The United States was the closest ally of the Kurds over the past few years. But in the end, the U.S. abandoned the Kurds, actually betraying them," Peskov told reporters.

In Ankara, Ibrahim Kalin, an Erdogan adviser, addressed one of the most heavily criticized aspects of Turkey's Syria buffer zone - a proposal to resettle up to 2 million Syrian refugees there. Refugee advocates have said the plan would violate international law if the Syrians were forcibly returned. Kurdish residents of northeast Syria fear that the plan, which would bring Sunni Arabs originally from other parts of Syria, would force demographic change in the region.

Erdogan and his ruling party have faced anger from the Turkish public over the country's hosting of up to 4 million Syrian refugees. In the months leading up to the Turkish military offensive, thousands of Syrians were deported during a crackdown on the refugees. Turkish officials have asserted that their departures were voluntary.

In their agreements with Turkey, neither the United States nor Russia mentioned the return of the many Kurdish and other civilians who have fled the border region in the past two weeks.

The senior administration official said, "I don't think we've seen any evidence of ethnic cleansing. That would be a very serious thing if it takes place."

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Cunningham and Fahim reported from Istanbul. The Washington Post's Missy Ryan in Washington contributed to this report.

This article was written by Karen DeYoung, Erin Cunningham and Kareem Fahim, reporter for The Washington Post.