President Obama said today he sympathizes with passenger complaints about aggressive body pat-downs at airports, but his counter-terrorism aides say they are necessary to guard against hidden explosives.

Balancing privacy and security is a "tough situation," Obama told reporters at a news conference following the NATO summit in Lisbon, Portugal.

"One of the most frustrating aspects of this fight against terrorism is that it has created a whole security apparatus around us that causes a huge inconvenience for all of us," Obama said.

Obama cited the attempted airplane attack by the so-called underwear bomber last Christmas as justification for aggressive security measures.

The president said he has told officials with the Transportation Security Administration to constantly refine and evaluate their procedures.

"I will also say that in the aftermath of the Christmas Day bombing, our TSA personnel are properly under enormous pressure to make sure that you don't have somebody slipping on a plane with some sort of explosive device on their persons," Obama said.

TSA and counter-terrorism officials say that at this point "the procedures they've been putting in place are the only ones right now that they consider to be effective" against hidden explosives, Obama added.

(Posted by David Jackson)