The war in Afghanistan began in 2001, following the attacks of September 11, more than seven years before Barack Obama became president. The Afghanistan fight, initiated during the presidency of George W. Bush, stands as the longest running war in the history of the country.
Pierson's comment came during an exchange with CNN's Victor Blackwell, when she was asked to explain the Republican nominee's recent assertion that President Obama is the "founder of ISIS." Trump has since called the comment sarcastic, "but not that sarcastic."
Pierson blamed the rise of ISIS on Obama and Hillary Clinton's opposition to the surge in Iraq, when she was a senator from New York.
"If you want to go way back, we can look at the troop surge, and after 2007 al Qaeda was essentially in ashes," Pierson said. "It was Barack Obama and Hillary Clinton who then destroyed the entire rollout by wanting to pull out early... That is the reason why ISIS is a global issue."
Then Pierson pivoted to the Afghanistan theater.
"Remember, we weren't even in Afghanistan by this time. Barack Obama went into Afghanistan, creating another problem," Pierson said.
Blackwell asked her to clarify, and she said, "That was Obama's war, yes."
Pierson went on to say, "I thought we were talking about the founding of ISIS. I mean ISIS came out of the Obama side of the war. Is that not a fact?"
Pierson later acknowledged the Afghanistan mission was not launched on Obama's watch.
Later Saturday, she took to Twitter in a bid to clarify her remarks. The spokeswoman blamed President Bill Clinton for failing to confront bin Laden and also called out Obama and Hillary Clinton for underestimating the potential growth of ISIS.
"Note: it was Bill Clinton that let Osama Bin Laden go forcing George Bush to deal with his failure to secure America," Pierson wrote. She followed it up with a second tweet, saying: "Since the media wants to ignore the policies/decisions made by Obama/Clinton in 2012, as I stated referencing the 8/12 DIA report."
ISIS began as a branch of al Qaeda based in Iraq, founded by Abu Musab al-Zarqawi
. Following his death in a US-led operation during President George W. Bush's tenure, the group reorganized itself amid the chaos of the sectarian violence in Iraq and the civil war in Syria. It eventually broke with al Qaeda and emerged as a self-declared "caliphate" known widely as ISIS, under the putative leadership of Abu-Bakr Al-Bagdadi.
In recent years, ISIS has expanded outside of Iraq and Syria, holding ground in Libya and Afghanistan.
Obama's opposition to the troop surge in Iraq as well as his general policies with regard to the war on terror and the rise of ISIS have been focal points of the campaign.
During the first year of his presidency, Obama approved a request
for more troops in Afghanistan, and as his administration has sought to bring the war to a close, he has acknowledged
that the US military's combat presence in Afghanistan will outlast his tenure.