visa restrictions for pakistani britons?

American officials, citing the number of terror plots in Britain involving Britons with ties to Pakistan, have expressed concern over a "loophole" which allows British citizens to enter the United States without a visa. According to the New York Times, in recent months, Secretary of Homeland Security Michael Chertoff has opened talks with the British government on how to curb the access of British citizens of Pakistani origin to the United States: U.S. Seeks Closing of Visa Loophole for Britons. The American embassy, however, has dismissed such reports about tightening visa restrictions: US denies curb on UK Pakistanis. So... what's really going on here?