- A majority of Americans say it's likely for terrorism to take place this week
- Thursday marks the 13th anniversary of the 9/11 attacks
- Rise in concern is likely due to the emerging threat of ISIS
The number of people who say that acts of terrorism are likely to occur around the anniversary of 9/11 has significantly increased from three years ago.
A new CNN/ORC International survey indicates that 53% of Americans believe it's likely for acts of terrorism to take place at this time, up from 39% in 2011 during the 10th anniversary of the attacks that killed nearly 3,000 people.
"It's likely that the change is due to newfound concerns over ISIS, which seven in 10 Americans believe has operatives within the U.S. able to commit an act of terrorism at any time," said CNN Polling Director Keating Holland.
The poll results come as President Barack Obama addresses the public Wednesday night on the threat of ISIS and lays out his strategy to combat the militant group in Syria and Iraq.
His prime-time speech falls on the eve of the 13th anniversary of the attacks.
September 11 also is the anniversary of the 2012 deadly attack against a U.S. compound in Benghazi, leaving four Americans dead, including the U.S. ambassador.
Most Americans, however, don't feel personally threatened by terrorism.
Just over four in 10 say it's likely that they themselves or a family member will become a victim of terrorism -- not a significant change from most previous years.
Women (49%) and senior citizens (48%) are most worried about terrorism, while men and younger Americans express much less worry, according to the poll.
For the survey, 1,014 adult Americans were interviewed by telephone from September 5-7. The sampling error is plus or minus 3 percentage points.