US Republican presidential candidate Rand Paul says Washington’s policy of supporting and arming anti-Damascus militants fueled the rise of (Daesh) ISIL terrorists.

Speaking at the fifth Republican Party debate on Tuesday night in Las Vegas, Nevada, Paul also distanced himself from his GOP rivals by warning against the United States pushing to militarily oust Syrian President Bashar al-Assad.

“We have to have a more realistic foreign policy and not a utopian one where we say, ‘Oh, we are going to spread freedom and democracy and everybody in the Middle East is going to love us.’ They are not going to love us,” Paul said.

He added that “by arming the allies of ISIS, the Islamic [sic] rebels [who were] against Assad, we created a safe space; we made that space bigger for ISIS to grow,” using an alternative acronym for the terrorist group.

The senator from Kentucky said “those who wanted a regime change had made a mistake.”

“I think when we toppled Gaddafi in Libya, I think, that was a mistake. I think ISIS grew stronger. We have a failed state and we’re more at risk,” he said.

He went on to say that “if you believe in regime change you are mistaken. In 2013, we put 600 tons of weapons – us, Saudi Arabia and Qatar – into the war against Assad. But pushing Assad back we did create a safe space [for Daesh].”

Syrian President Bashar al-Assad

Syria has been gripped by deadly violence since March 2011. The United States and its regional allies - especially Qatar, Saudi Arabia and Turkey - have been supporting the terrorists operating inside Syria since the beginning of the crisis.

The foreign-sponsored war against the Syrian state and people has killed more than 250,000 people and driven more than 10 million from their homes.

Elsewhere in his remarks, Senator Paul also slammed Republican presidential frontrunner Donald Trump, saying his policies infringe on the US Constitution.

"Is Donald Trump a serious candidate?" Paul asked, accusing him of wanting to close the Internet and kill families of terrorists.

“It would defy every norm that is America, so when you ask yourself, whoever you are, if you think you’re going to support Donald Trump, think: Do you believe in the Constitution?” Paul said. “Are you going to change the Constitution?”