The United States president is vowing to hunt down those behind the failed Christmas Day bomb attack on an American airliner over Detroit.
In a televised address from Hawaii, where he's holidaying with his family, Barack Obama says he will use every element of national power to thwart enemies trying to attack the United States.
He's announced an inquiry into how the man charged with trying to blow up the plane had been able to board it in Amsterdam.
Mr Obama also says he has ordered a second review to examine all screening policies, technologies and procedures related to air travel.
He says increased security measures are in place and his administration will not rest until those responsible for the attempted bombing are tracked down.
Al Qaeda claims responsibility
Al Qaeda's regional wing in the Arabian Peninsula earlier said it was behind the failed attack on a US passenger jet.
It said the attack was to avenge US attacks on the group in Yemen, according to a statement posted on Islamist websites.
Al Qaeda said it had provided the suspect with the explosive device but it failed to detonate because of a technical fault.
A 23-year-old Nigerian, Umar Farouk Abdulmutallab, has been charged with trying to blow up the airliner on a flight to Detroit.
He was overpowered by passengers and crew on the Northwest Airlines flight 253 from Amsterdam to Detroit on Christmas Day, after attempting to detonate an explosive device attached to his body.
Mr Abdulmutallab was on a US list of possible security threats - which contains more than half a million names - and was travelling with a valid US visa.
Immediate security measures put in place after the Christmas Day attack included the placing of federal air marshalls on flights entering and leaving the United States, Mr Obama said.
US official admits air travel security failed
The head of homeland security in the United States, Janet Napolitano, has conceded airport security systems failed, allowing the Nigerian man to smuggle explosives onto a US passenger plane.
Ms Napolitano says a thorough review is underway, and an earlier remark of hers that the security system had worked was taken out of context.
"These are procedures that have been in place since the shoe-bomber in 2006", she was quoted on the BBC as saying, and the review would look at what needed to be upgraded and improved.
The first federal court hearing for the suspect, which had been due to take place on Monday afternoon in Detroit, was cancelled, CNN reports. No reason was given.
NZ travellers urged to avoid US stopovers
The Travel Agents' Association of New Zealand says it doesn't expect travellers to cancel or postpone flights to the US because of stepped up security measures.
Chief executive Paul Yeo says people should avoid transiting through the US if they're heading to Europe and are unhappy about the more stringent checks.
Mr Yeo says travellers could instead travel via Asia.