After leading a moment of silence at the White House to mark the first attack of Nine Eleven, President Donald Trump honored the victims of that day in a ceremony at the Pentagon, vowing to safeguard the U.S. homeland from further terrorist strikes, saying American 'cannot be intimidated.'

"Those who try will soon join the long list of vanquished enemies who dared to test our mettle," Mr. Trump said on a gorgeous, sun-filled September morning, much like September 11, 2001, when nearly 3,000 people lost their lives after terrorists hijacked four passenger jets, destroying both towers of the World Trade Center in New York, gouging a huge hole in the Pentagon, and then plunging the last plane into a farmer's field in Shanksville, Pennsylvania.

"Though we can never erase your pain, or bring back those you lost, we can honor their sacrifice by pledging our resolve to do whatever we must to keep our people safe," the President said outside the Pentagon, where a giant American flag was hung near the point where a hijacked jetliner was intentionally crashed into the building, killing 184 people.

"On that day, not only did the world change, but we all changed," Mr. Trump said.

"The horror and anguish of that dark day were seared into our national memory forever," Mr. Trump added. "It was the worst attack on our country since Pearl Harbor."

Before his speech on the 9-11 attacks, the President noted the major breaking news story of this day, the damage from Hurricane Irma, as he promised the people of Florida that his administration would help them recover from the storm that raced ashore on Sunday.

"We're marshaling the full resources of the federal government," Mr. Trump said.

"When Americans are in need, Americans pull together," the President said of the needs for victims of both Hurricanes Harvey and Irma.

But the focus of the President's remarks were looking back 16 years ago, to the horrible morning of carnage, which set in motion years of U.S. military actions in what was labeled, the "War on Terror."

"America does not bend, we do not waver," Mr. Trump declared, making clear that his administration would continue to pursue terror groups around the world that try to do harm to the United States.