Former Presidential candidate Hillary Clinton tweeted: "The president sided with authoritarian authorities in Turkey and Russia at the expense of our loyal allies and the US interest. This decision is an odious betrayal of the Kurds."
Republican House Representative Mark Rubio expressed concern about Trump's recent decision: "If reports of US retreat in Syria are accurate, the Trump administration has made a grave mistake that will have implications far beyond Syria."
He added: "Iran will then be encouraged to escalate hostile attacks which in turn could lead to a wider and more serious regional war."
"If we are to be supported by our allies, we should support them equally," said former US ambassador to the UN Nikki Haley adding, "the SDF was helpful in our successful fight against ISIS in Syria.
Rep. Liz Cheney, a member of the House leadership, called Trump's decision "a catastrophic mistake that puts our gains against ISIS at risk and threatens US security."
"This decision ignores the lesson of 9/11. Terrorists thousands of miles away can use their safe havens to launch attacks against America," he said in a tweet.
"The withdrawal of US troops from the region will give a signal that we are giving the message that we will abandon our friends and give Russia and Iran exactly what they want," said Representative Kizner.
"I don't strongly agree with Trump to allow Erdogan to invade Syria. This is a betrayal of the Kurds, strengthens ISIS and puts the American homeland at risk," said Rep. Pete King, a member of the Intelligence and Homeland Security committees.
"The Syrian Kurds stood with us in the war against ISIS when Turkey did not. Trump's decision to betray them is unreasonable. Congress should make it clear that Turkey will pay a heavy price if it attacks the Syrian Kurds," said Chris Van Hollen, a US senator.
Former US politician and presidential candidate Mike Huckabee also noted that he generally agrees with Trump's foreign policy not to fight foreign wars on behalf of anyone, but called Trump's decision to withdraw his troops from Syria and abandon the Kurds a "big mistake." But most of what they hope, according to Huckabee, is to give them the tools to defend themselves. They were sincere allies and we cannot abandon them.