WASHINGTON — Sen. Mitt Romney and other senators Tuesday pushed back against a senior American envoy’s defense of the Trump administration’s withdrawal of troops in northern Syria.

James Jeffrey, the president’s special representative for Syria engagement, blamed Turkey’s violation of an agreement for the ensuing chaos that is realigning alliances in the Middle East.

“They went in despite a very carefully packaged set of incentives and sticks to get them to stay with the security agreement we had done in August,” Jeffrey said. “And suddenly, President Erdogan told President Trump he wasn’t going to stick with it and he was coming in.”

Testimony before the Senate Foreign Relations Committee came the same day Turkey and Russia agreed to jointly patrol almost the entire northeastern Syrian border after the withdrawal of Kurdish fighters. The ramifications of allowing Russia, which backs Syria, to fill the void was not lost on senators who lamented the United States’ waning influence in the region after President Donald Trump withdrew troops that fought alongside Kurdish forces against the Islamic State.

“As the pause of hostilities expires, as we sit here, it’s clear that the United States has decided Russia and the murderous (Syria President Bashar Hafez al-) Assad regime are calling the shots,” said the committee’s ranking Democrat, Sen. Bob Menendez, of New Jersey.

He and committee chairman, Sen. James Risch, R-Idaho, called on fellow senators to support congressional sanctions on Turkey if it continues its offensive.

“If Turkey maintains its aggressive path, it must bear a cost for undermining U.S. security interests,” Risch said.

The committee called Jeffrey to testify two weeks after Trump announced via Twitter that he was removing U.S. troops from Syria, which senators and others have said cleared the way for Turkey’s offensive against the Kurds.

But Jeffrey said the troops were withdrawn to protect them from an inevitable incursion of Turkish and Russian-backed troops seeking to push out the Kurds and lay claim to the region.

“Our troops would be caught in the middle and so it was a prudent decision taken by our military leaders to get those troops out of the way,” he said.

Jeffrey’s explanation of what precipitated the U.S. pullout came in response to questions from Romney, R-Utah, who disagreed with Jeffrey’s testimony that Trump’s decision and Turkey President Recep Tayyip Erdogan’s launch of an offensive against the Kurds hours later were unrelated.

“Erdogan basically said, ‘We’re coming in, get out of the way.’ And America blinked. Am I reading that wrong?” Romney asked.

Jeffrey said Romney was reading his statement correctly.

He noted, however, that U.S. forces were not in the region to engage in battle with Turkey. He said only about two dozen troops manned two observation outposts in the area the Turkish forces invaded. The remaining U.S. troops that have evacuated to Iraq were further south.

Jeffrey later said if U.S. troops were given orders to resist Turkish aggression then Erdogan would have “thought twice” about pushing the Kurds out of the region.

Last week, Romney blasted the Trump administration’s decision to withdraw U.S. troops from the region.

“What we have done to the Kurds will stand as a bloodstain in the annals of American history,” the senator said Thursday on the Senate floor.

During Tuesday’s hearing, Jeffrey said he was not given a heads-up before Trump announced in a tweet that U.S. troops were leaving northeastern Syria. He told Romney Kurdish forces were told immediately after the announcement.

Romney asked if negotiations between Turkey and “our Kurdish allies” could have prevented the bloodshed that resulted from the American withdrawal.

Jeffrey said the negotiations were taking place up to the moment Turkey launched its offensive. He explained that Erdogan was warned his offensive would be unsuccessful and that the events of the past week have borne that out.

Kurdish fighters have “not been really defeated or eliminated from the game. So that Turkish objective was not achieved, and Turkey has not gained much territory,” Jeffrey said. “We told (Erdogan) all along that this would happen and that if they did that they would run into a great deal of trouble with us, thus the sanctions and the other steps we took against them 10 days ago now.”

However, reports of the agreement between Erdogan and Russian President Vladimir Putin earlier in the day paint a different picture for Turkey, Russia and Syria.

“Turkey would get sole control over areas of the Syrian border captured in its invasion, while Turkish, Russian and Syria government forces would oversee the rest of the border region,” the Associated Press reported. “America’s former U.S. allies, the Kurdish fighters, are left hoping Moscow and Damascus will preserve some pieces of their autonomy dreams.”

U.S. troops in Syria fought alongside Kurdish-led forces for five years in northeast Syria, where they defeated the Islamic State at the cost of thousands of Kurdish fighters’ lives.