The shadow of a renewed terror threat has been hanging over today's observances of the 13th anniversary of the September 11th terrorist attacks.

The events come hours after President Barack Obama said he would open a new military front in the Middle East -- authorizing airstrikes inside Syria along with expanded strikes in Iraq in an effort to root out Islamic State extremists.

In remarks at the Pentagon this morning, Obama didn't mention the plan to step up military and diplomatic action against that group. He said that 13 years after the terror attacks, ``America stands tall and America stands proud.''

At the World Trade Center site in New York, family and friends read the names of the nearly 3,000 people killed there, at the Pentagon and near Shanksville, Pennsylvania.

One woman wept as she read the name of her father, and said, ``You put me to bed 13 years ago not knowing it would be your last time.''

The memorial plaza was closed to the public for most of the day, available only to family members.

In Pennsylvania, former House Speaker Dennis Hastert donated the flag that flew atop the U.S. Capitol on 9/11 to the Flight 93 National Memorial. He said the Capitol may not have remained standing 13 years ago if the United Airlines passengers and crew had not rebelled against four hijackers.