In a statement issued on Monday evening, Mr Obama also vowed to track down the plotters behind the attempted Christmas Day aeroplane bombing attack.
He said the attack was a serious reminder of the danger his nation faced.
Mr Obama said he also had ordered a thorough review of the airport screening process to determine how the alleged bomber, Umar Farouk Abdulmutallab, was able to fly into the United States.
Commenting on an attempt to bomb a US airliner while it was landing in Detroit, the president said he had directed his national security team to keep up the pressure on those who would attack his country. “We do not yet have all the answers about this latest attempt, but those who would slaughter innocent men, women and children must know that the United States will do more than simply strengthen our defences,” he said.
“We will continue to use every element of our national power to disrupt, to dismantle and defeat the violent extremists who threaten us, whether they are from Afghanistan or Pakistan, Yemen or Somalia, or anywhere where they are plotting attacks against the US homeland.”
Mr Obama noted that apparently the suspect in the Christmas incident was in the US security system, but not on a watch list, such as the so-called no-fly list.
“So I have ordered a thorough review, not only of how information related to the subject was handled, but of the overall watch list system and how it can be strengthened,” he said.
The second review would examine all screening policies, technologies and procedures related to air travel, he added. “We need to determine just how the suspect was able to bring dangerous explosives aboard an aircraft and what additional steps we can take to thwart future attacks.”