WASH INGTON (AFP) - The Obama administration tried Sunday to quell an uproar over pat-downs at US airports, with air travelers in revolt against the new security measures described by some as invasive and humiliating. Just days before the start of the Thanksgiving holiday the years busiest travel weekend which will see hundreds of thousands of passengers descend upon US airports Americans have been balking en masse against the probing physical searches meant to find hidden explosives or weapons. The pat-downs, which were put into place at the beginning of the month, are an alternative for passengers who opt out of full body X-rays, which some complain reveal the contours, and more, of a passengers body, and not just potentially dangerous weapons. But some passengers say the manual searches, in which agents use their fingers and open palms to search for explosives or concealed weapons, are just as bad as the scanning machines, and complain that they come uncomfortably close to the genital area.John Pistole, head of the federal Transportation Security Administration (TSA), acknowledged the uproar on Sunday but insisted the new security measures would not be scrapped. Do I understand the sensitivities of people? Yes. If youre asking, am I going to change the policies? No, he told CNN. Pistole reminded the public that the stringent measures were put in place to help plug perceived holes in US security at a time of continuing terrorism threats. The more intimate pat-downs and full body scanners were introduced in the wake of a string of foiled bomb plots against US-bound airliners. Those include the Christmas Day bomb attempt last year when Abdul Farouk Abdulmutallab, a young Nigerian, allegedly tried to ignite explosives concealed in his underwear as his plane came in to land in Detroit. The decision to tighten security hinges on what the current threat environment is, given the current threat stream being informed by the latest intelligence, Pistole told CNN. We know that we face a determined enemy who has been adept at devising and concealing explosive devices, bombs, that will target not only aviation in terms of commercial aircraft but also cargo aircraft, said Pistole, who also appeared before a US Senate committee last week to testify about the controversial procedures. Still, he acknowledged that the measures had caused widespread discontent across the United States, and said he was sympathetic to the public debate. The challenge is, how do we balance the security that everybody wants everybody wants to make sure they get to their destination safely with the privacy that everybody wants also? How do we find that precise blend for each person? Pistole said. Even Secretary of State Hillary Clinton Sunday who acknowledged passenger concerns over new procedures, admitted reservations when asked if she would submit to such a pat-down. No, not if I could avoid it. I mean who would? she admitted on CBSs Face the Nation. The US top diplomat noted however that the measures were brought in because terrorists keep getting more creative about what they do to hide explosives and, you know, crazy things like underwear. I think that we have to be constantly asking ourselves: how do we calculate the risk? You know, sometimes we dont calculate it correctly, we either overstate it or understate it, Clinton said. The TSA has put hundred of full body scanners in scores of airports across the United States, with a goal of installing some 500 of the devices across the country by the end of the year, and 1,000 by the end of 2011. But there has been greater than anticipated public pushback against the security measures. A loose network of groups are calling for a boycott of the full body scanners on November 24, the day before Thanksgiving a protest that threatens to gum up the works at airports across the nation on one of the biggest travel days of the year. Called National Opt Out Day, the campaign could cause long delays in security lines if many passengers refuse to go through the body scanners and are subsequently subjected to the slower, personnel intensive pat-downs. Meanwhile, one passengers particularly vocal protest went viral on the Internet, when a TSA official trying to pat him down. If you touch my junk Ill have you arrested, he was heard warning a TSA screener.