ISTANBUL - President Donald Trump's announcement of a U.S. withdrawal from northern Syria, paving the way for a Turkish military operation against a Kurdish militia in the area, is widely being seen as a diplomatic triumph for Turkey's President Recep Tayyip Erdogan.

Trump made the surprise move in a telephone conversation with Erdogan on Sunday.

Monday, Erdogan welcomed Trump's resetting of Washington policy toward Syria, indicating a Turkish operation could be imminent.

"We have said [in the past] that may suddenly arrive one night. We remain determined," Erdogan said.

For months, Turkish forces have been massed on the Syrian border facing off against the Kurdish-led Syrian Democratic Forces. Ankara designates the YPG, the main force within the SDF, as terrorists, but the group is a critical ally in the Washington-led war against the Islamic State terror group.

Under U.S. pressure, Ankara has held off from its plan to create a 30-kilometer-deep buffer zone to protect its border from the Kurdish militia. Erdogan also plans to use the territory to send back up to 2 million Syrian refugees living in Turkey.

FILE - Turkish and American forces conduct their first joint ground patrol in the so-called "safe zone" on the Syrian side of the border with Turkey, seen in the background, near Tal Abyad, Syria, Sept. 8, 2019.

Washington's support of the YPG has been a significant point of tension with Ankara. Analysts suggest Erdogan will likely strike quickly against the Kurdish militia.

"There is the possible expectation Trump may step back," said international relations professor Huseyin Bagci of Ankara's Middle East Technical University, "because of the historical experiences of what happened in previous years. Turkey does not trust either President [Barack] Obama or Trump. The general concept is don't trust American presidents."

Amid domestic criticism of his decision regarding northern Syria, Trump on Monday issued a warning to Turkey.

"If Turkey does anything that I, in my great and unmatched wisdom, consider to be off limits, I will totally destroy and obliterate the Economy of Turkey (I’ve done before!)," he tweeted.

In December, Trump, in another call with Erdogan, promised to withdraw all U.S. forces from Syria immediately. But following intense political pressure, the withdrawal was suspended. Analysts say Ankara will be watching Washington closely, where already there is strong pushback from some close allies of the U.S. president over Sunday’s decision.

"It will be a stain on America's honor for abandoning the Kurds," tweeted Republican Sen. Lindsay Graham. "if this plan goes forward, will introduce Senate resolution opposing and asking for a reversal of this decision. Expect it will receive strong bipartisan support."

Graham, a close Trump ally, was seen as instrumental in persuading Trump last year to step back from withdrawing forces from Syria.

Ankara is also likely to face pressure from Tehran over its Syrian plans.

"The only way to maintain the security of Turkey is the military presence of the central government in the border areas," Iranian Foreign Minister Javad Zarif said Sunday. "It is not possible to ensure security by working against the territorial integrity and sovereignty of Syria."

FILE - Iran's Foreign Minister Javad Zarif reacts during a news conference in Moscow, Russia, Sept. 2, 2019.

Zarif said Tehran's position was "frankly" put to Ankara, at last month's tripartite summit with Moscow. The three countries are working together to resolve the Syrian conflict under what is called the "Astana Process."

Turkish Foreign Minister Mevlut Cavusoglu pushed back Monday against Zarif.

"From the start of the Syria war, we have supported that country's territorial integrity and will continue to do so from now on," Cavusoglu tweeted.

Tehran and Ankara are regional rivals and support opposite sides in the Syrian civil war. Iran is already voicing unease over Turkey's existing military presence in Syria, issuing thinly veiled calls for their withdrawal.

Turkey's planned operation of creating a 30-kilometer buffer zone will mark a significant expansion of Turkish military presence in Syria. However, Trump's suggestion that Ankara takes over the fight against Islamic State and control of jihadist prisoners in the region could see a significant expansion of the planned operation.

"What I know is that Turkey probably got assurances [from Washington] that it can widen this 30 km range," said Bagci. "Technically speaking, the Turkish military has taken every measure to go at least 100 kilometers inside Syria. I know this from military sources."

Bagci says it remains unclear whether the Turkish air force will be able to use Syrian airspace for its planned operation.

Currently, the airspace is under U.S. control, which has been enforcing a de facto no-fly zone. Washington has not commented on whether it will allow Turkish warplanes to enter.

"Without air support, they [Turkish army] would have to rely on artillery, mortar and perhaps tanks," said retired Turkish general Haldun Solmazturk, a veteran of cross-border operations.

"It is inevitable there would be resistance by the YPG, and this would be in a huge area," he added." There would be an insurgency if the Turkish military moves there and stays there. It will be a costly operation."