In the most heated exchange of this morning's Senate Foreign Relations Committee hearing on the Benghazi attack, Sen. Ron Johnson (R-Wisc.) took on Secretary of State Hillary Clinton over the Obama administration's initial claims that the assault "sprang out of" protests. He said the American people could have been told "within days" that the protests over an anti-Muslim video were not going on in Benghazi.

Clinton responded forcefully to Johnson, "With all due respect, the fact is we had four dead Americans! Was it

because of a protest or was it because of guys out for a walk one night who decided they'd go kill some Americans? What difference, at this point, does it make? It is our job to figure out what happened and do everything we can to prevent it from ever happening again."

Watch the full exchange: