The U.S. was accused of an “aggression” by the Syrian regime on Thursday after Secretary of State Rex Tillerson said the U.S. military will maintain a presence in Syria just days after Damascus said it is determined to drive out the troops.

Tillerson told the Stanford University audience on Wednesday that the focus of U.S. military will be to prevent ISIS from re-emerging. He outlined a broader strategy for the troops, including forcing Syrian President Assad to resign from power.

The remarks come shortly after the Syrian regime called any plans for further involvement by the U.S. in the region a “blatant assault” on the country’s sovereignty, according to the state media.

The regime was responding to reports on the creation of a new U.S.-backed border force in the country.

The U.S.-led military coalition is training a new border force comprised of recruits and the Kurdish-led Syrian Democratic Forces that is expected to reach 30,000 members and secure areas recently liberated along its border with Turkey and Iraq.

But the Syrian government doubled-down on their opposition to the U.S. on Thursday, issuing a statement calling the U.S. plans to remain in Syria an “aggression” and pledged to liberate the country from any “illegitimate” foreign presence.

“The American military presence on Syrian land is illegitimate and represents a blatant breach of international law and an aggression against national sovereignty,” the Syrian Foreign Ministry’s statement read, according to Reuters.

The ministry added it will carry on its “relentless war against terrorist movements with their different names until every inch of Syrian soil is cleansed” and will combat any “illegitimate foreign presence” with “the same determination”.

Tillerson emphasized the importance of avoiding President Obama's "mistake" of prematurely pulling out U.S. troops from Iraq.

"We cannot allow history to repeat itself in Syria,” he said. “ISIS presently has one foot in the grave and by maintaining an American military presence in Syria until the full and complete defeat of ISIS is achieved, it will soon have two.”

Despite Iranian and Russian support for Assad, Tillerson said the U.S will attempt to isolate the Syrian regime government by cutting off international reconstruction aid flows to any parts of the country controlled by Assad.

"Once Assad is gone from power, the United States will gladly encourage the normalization of economic relationships between Syria and other nations,” he said.

The Associated Press contributed to this report.