Trump vows to protect Americans from 'savage killers'

United States President Donald Trump and first lady Melania Trump joined the nation by observing a minute's silence to mark the 16th anniversary of the September 11 terror attacks, which killed nearly 3,000 people by issuing a stern warning to extremist groups threatening the U.S.

"The terrorists who attacked us thought they could incite fear and weaken our spirit,But America cannot be intimidated and those who try will soon join the list of vanquished enemies who dared to test our mettle," President said.

Speaking at the Pentagon, where one of three hijacked planes crashed 16 years ago today, Trump mourned those who died and said he would honor the sacrifice by doing "whatever we must to keep our people safe."

President vowed U.S. armed forces would ensure al Qaeda and other extremist groups would never be given a "sanctuary" from where they could plot and launch a similar attack again.

"We are making plain to these savage killers that there is no dark corner beyond our reach," the President said.

"When America is united, no force on earth can break us apart," Trump added.

"The horror and anguish of that day were seared into our national memory forever," Trump said. "On that day not only did the world change, but we all changed. Our eyes were opened to the depths of the evil we face.

"But in that hour of darkness," he continued, "we also came together with renewed purpose. Our differences never looked so small, our common bonds never felt so strong."

The U.S. President laid a wreath at a Pentagon observance also attended by Defense Secretary James Mattis and Marine Corps Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff.