"[Clinton is] the very person who stood by while the conflict in Syria became the worst humanitarian crisis in a generation," Rubio stated in his speech at the American Legion.
He also accused Clinton of pushing the "reset" button with Russia when Moscow was accused of allegedly assaulting the sovereignty of its neighbors.
Moreover, Rubio added that Clinton "resorted to half-measures in Libya instead of doing what it would take to prevent terrorists from taking hold — terrorists who ultimately took the lives of four Americans in Benghazi."
He warned that "not only is Hillary Clinton incompetent, she is a liar."
Over the course of Clinton’s presidential campaign, she has come intense scrutiny for using a personal e-mail account and server for official government business during her tenure as secretary of state from 2009 to 2013.
The Democratic frontrunner’s emails revealed messages exchanged during the Islamic terrorist attacks on the US diplomatic compound in Benghazi, Libya in September 2012, in which four US government employees were killed, and her handling of situation.