Rex Tillerson testifies during a Senate Foreign Relations Committee confirmation hearing to become U.S. Secretary of State on Capitol Hill in Washington, January 11, 2017.

The U.S. will stand up against anyone who commits crimes against humanity, Secretary of State Rex Tillerson said on Monday, less than a week after Washington launched missile strikes in response to an alleged Syrian chemical attack.

"We rededicate ourselves to holding to account any and all who commit crimes against the innocents anywhere in the world," Tillerson told reporters while commemorating a German Nazi massacre committed in Italy in 1944.

The U.S. attacked the Syrian air base in retaliation for what it said was a chemical weapons assault by Syrian President Bashar Assad that killed dozens of civilians, including many children.



