It was a speech that Barack Obama - a war-stopping, Nobel Peace Prize-winning President - never wanted to give.
A year after he pulled back from threatened military attacks on Syria over chemical weapons, Obama told America he now would launch airstrikes against ISIS targets in the country wracked by civil war.
The nationally televised address on Wednesday night, which lasted less than 15 minutes, promised far-reaching impact that could embroil the nation in another Middle East conflict.
"This was a very difficult speech for him," CNN chief political analyst Gloria Borger said of a President who campaigned on ending wars in Iraq and Afghanistan. "He's inserted us into the middle of a Syrian civil war."
The plan to "dismantle and ultimately destroy" the Sunni jihadists who have taunted America by beheading two captive U.S. journalists calls for what CNN chief national security correspondent Jim Sciutto described as a "tremendous turnaround" in Obama's previous policies in the region.
After previously rejecting calls from top advisers to arm and train some of the Syrian rebels fighting President Bashar al-Assad and ISIS, Obama now seeks specific congressional approval to do so.
He also threatened airstrikes on ISIS targets in a major expansion of a campaign in Iraq previously limited to protecting U.S. advisers working with Iraqi forces and preventing the slaughter of minority groups by the extremists also known as ISIL and the Islamic State.
"I have made it clear that we will hunt down terrorists who threaten our country, wherever they are," Obama said. "That means I will not hesitate to take action against ISIL in Syria, as well as Iraq. This is a core principle of my presidency: if you threaten America, you will find no safe haven."
In addition, 475 more U.S. military advisers are headed to Iraq, raising the total of American forces there to 1,700 for a mission originally described as limited.
See more on this developing story on CNN.com