During Sunday’s night debate, Hillary Clinton did her best to fend off a more aggressive Donald Trump, but let slip an incredible gaffe under a determined assault on her foreign policy record from the GOP nominee.

Generally seen as winning or holding his own after an initial debate loss, Trump, the Republican presidential nominee, pressed Clinton, the former secretary of state, on foreign policy failures during her tenure.

“Her revisionist assessment of her role as secretary of state cannot efface the reality that she supported Obama’s issuance of the red line and never disavowed the president’s craven capitulation.”

Speaking at the town hall forum at Washington University at St. Louis, Trump was prodding Clinton on President Obama’s warning to Syria — the famous “red line” speech — when Clinton interrupted with a rather amazing falsehood.

“I was gone,” said Clinton. “At some point, we need to do some fact-checking here.”

It was a key moment. It shows when Trump stays on message, he causes Clinton to buckle. Here, she flat-out told a falsehood. It’s hard to comprehend how she did not know this was a lie — at best, a half-truth.

[lz_jwplayer video=DvUcUboS]

President Obama’s “red line” speech was given Aug. 20, 2012, at the White House. Clinton was secretary of state, the nation’s chief diplomat, from early 2009 to early 2013. The “red line” speech was in fact a threat made against Syria, or any nation that used chemical weapons.

Clinton was perhaps referring to an actual threat of warfare in the summer of 2013, after she had left.

On Aug. 21, 2013, the Syrian military attacked rebel-controlled areas of the Damascus suburbs with chemical weapons, killing nearly 1,500 civilians, including more than 400 children, according to Derek Chollet, a former Pentagon and State Department official under Obama, writing for Politico.

Obama decided it was time to enforce the red line, which he set in 2012: “We cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people,” Obama told reporters at the White House, according to CNN. “We have been very clear to the Assad regime — but also to other players on the ground — that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus; that would change my equation.”

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

But over the next month in the fall of 2013, Obama declined to order strikes on Syria, as he could have, without consulting Congress. Instead, he punted to Congress, who declined to give him an official authorization of force.

Meanwhile, the State Department worked behind the scenes to avoid having to enforce the red line. Russia became involved, and soon Syrian dictator Bashar al-Assad agreed to turn over all chemical weapons. Obama counted the diplomatic solution as victory.

But according to Obama’s critics, the failure of Obama to enforce the red-line rhetoric showed America’s leaders to be weak — everywhere on the globe.

“Obama draws the line in the sand,” Trump said during Sunday’s night debate. “It was laughed at all over the world.”

Clinton herself has deeper connections to the policy than she admitted. Trump has now forced an examination of that record.

“Hillary Clinton began her tenure as secretary of state calling Assad a reformer,” said Robert G. Kaufman, a professor of public policy at Pepperdine University, in an email to LifeZette. “It was Hillary Clinton that named the reset with Russia as secretary of state she now disavows. Her revisionist assessment of her role as secretary of state cannot efface the reality that she supported Obama’s issuance of the red line and never disavowed the president’s craven capitulation, literally inviting [Vladimir] Putin’s Russia to fill the void and lowering the barriers to aggression everywhere.”

[lz_related_box id=”215323″]

It shows when Trump sticks to the script, he can rattle Clinton. Trump’s pressing of Clinton on jobs and foreign policy seems to have rattled Clinton far more than bringing up President Bill Clinton’s extramarital affairs.

Clinton seemed dumbstruck as she begged the debate’s moderators to fact-check Trump.

It’s a good thing for her they didn’t.

“Hillary Clinton’s ill-advised support for Obama’s feckless Syria policy not only lowered the barriers to aggression in the Middle East, but also in Ukraine and the South and East China Seas, where Putin and the Chinese Politburo took due measure of American weakness,” said Kaufman.