Today marks the 13th anniversary of the Sept., 11, 2001, terrorist attacks on the United States.

The anniversary has taken on more ominous significance due to the rise of the Islamic State in Iraq and Syria (ISIS).

In a nationally televised speech last night, President Barack Obama said it’s time to go after ISIS in Iraq and Syria. The president said the U.S. will expand its airstrikes against the Sunni jihadists in Iraq to target them across the border in Syria.

“I have made it clear that we will hunt down terrorists who threaten our country, wherever they are,” he 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.”

The president said the counterterrorism campaign will be waged with air power and support for partner forces on the ground.

The President also announced another 475 American military advisers would go to Iraq, pushing the total figure to more than 1,000.

Also Wednesday, Obama shifted $25 million in military aid to Iraqi forces, including Kurdish fighters in the north combating the ISIS extremists. The aid could include ammunition, small arms and vehicles, as well as military education and training.

Former U.S. ambassador Ryan Crocker, who served in Syria, Iraq, Afghanistan, and Pakistan, said on Wednesday that ISIS presents a bigger threat to America than al Qaeda, which organized the 2001 terrorist attacks.