Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

JERUSALEM — President Donald Trump will not withdraw American troops from northern Syria until the Turkish government guarantees it won’t then attack Syrian Kurdish forces that have been critical allies in the fight against ISIS, national security adviser John Bolton said Sunday.

Bolton said a commitment from Turkish President Recep Tayyip Erdogan that protects the Kurds after American forces exit is something Trump is demanding, and that it’s just one of several conditions that have to be met before U.S. troops leave.

“There are objectives that we want to accomplish that condition the withdrawal,” Bolton said.

John Bolton is shown around Jerusalem's Western Wall, the holiest site where Jews can pray. Carol E. Lee

He spoke to reporters traveling with him to Israel and Turkey as he tried to clarify Trump’s Syria withdrawal policy for allies. He’s meeting with Israeli officials Sunday and Monday, and with Turkish officials, including Erdogan, on Tuesday.

Since Trump abruptly announced on Dec. 19 that all U.S. forces in Syria would exit immediately, administration officials have shifted the timing to say it would happen more slowly. Officials are now setting a series of conditions for withdrawal that must first be met, which Bolton described as “policy decisions that we need to implement.”

“This is a cause and effect mission,” Bolton said. “Timetables or the timing of the withdrawal occurs as a result of the fulfillment of the conditions and the establishment of the circumstances that we want to see. And once that’s done, then you talk about a timetable.”

Bolton also indicated that the U.S. troop withdrawal will not be a complete drawdown, as Trump had promised. Instead, he discussed a withdrawal of American forces from northern Syria, where most of the estimated 2,000 U.S. troops are based, while leaving some of them in the southern part of the country.

Stressing that despite conditions for withdrawal,the continued presence of U.S. forces in Syria is not unlimited.

“The primary point is we are going to withdraw from northeastern Syria," Bolton said.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

“So it’s going to be a different environment after we leave, there is no question about that,” he added. “But there is no desire to see Iran’s influence spread that’s for sure.”

Trump also commented Sunday on the timing of the withdrawal. "I never said we’d be doing it that quickly," the president said from the White House. "We won’t be finally pulled out, until ISIS is gone.”

The remark came in contrast to the president's statement from Dec. 19., when he said the withdrawal would happen quickly and that the U.S. had defeated ISIS. "Our boys, our young women, our men, they're all coming back and they're coming back now," Trump said at the time. "We won."

In his remarks delivered abroad, Bolton also touched on a key base where the U.S. and other allies have a couple hundred troops stationed.

"Then there is the Al Tanf garrison, which is still very strategically important in connection with our determination that Iran not achieve this arc of control stretching from Iran through Iraq into Lebanon and into Syria," he said.

Al Tanf started out as a base to train fighters against ISIS but has morphed into playing a critical role in the U.S. effort to diminish Iran's influence in the region.

It’s unclear what the U.S.’s legal justification would be for maintaining troops there, although Bolton cited Article II of the Constitution, which names the president the Commander-in-Chief of the country's armed forces.

“I think there’s plenty of legal justification about concern for the resurgence of ISIS,” he said. “But I’m a strong believer in Article II, and I think that what that means is the president has full authority to protect American and allied interests anywhere around the world.”

Iran is the main focus of Bolton’s meetings in Israel. Al Tanf is located along a critical road that stretches from Tehran to Baghdad to Damascus and sits in the heart of what Iran hopes will be part of a "Shiite Crescent” — a continuous land bridge linking Iran through Iraq and Syria to Lebanon.

While Trump's withdrawal announcement was greeted with dismay in Israel, which sees U.S. involvement in the region as key to constraining Iran, Israeli Prime Minister Benjamin Netanyahu welcomed Bolton warmly and called him an "old friend."

"I will discuss with his people efforts to stop the Iranian aggression in our region, the situation in Syria — following President Trump's decision," he said at the start of a Cabinet meeting Sunday. "Our position is clear — we continue to act against the Iranian military buildup in Syria, including these days, and we are acting against anyone who undermines or tries to undermine Israel's security."

In Turkey, Bolton will face a defiant Erdogan, who considers the Kurdish forces in Syria to be terrorists who threaten Turkey's stability.

He warned Turkey against taking any military action in Syria without consent from the U.S.

"We don't think the Turks ought to undertake military action that's not fully coordinated with and agreed to by the United States, at a minimum so they don't endanger our troops, but also so that they meet the president’s requirement that the Syrian opposition forces that have fought with us are not endangered,” Bolton said.

He said the U.S. has “told the Kurds our best judgment is that you stand fast now.”

Erdogan's spokesman said on Sunday it was irrational to claim Turkey targets Kurds, saying Ankara's targets were ISIS militants and the Kurdish groups YPG and PKK, state-owned Anadolu news agency reported.

Bolton will be joined in Ankara by Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford and Ambassador James Jeffrey, who was named Friday as the Special Envoy for the Global Coalition to Defeat ISIS.

He said Dunford will remain in Turkey after Tuesday to continue discussions with Turkish officials.