U.S. authorities say the British ringleader of the plot has been identified and is in custody in Pakistan along with two of his co-conspirators. Authorities say Rashid Rauf was essentially running the plot by remote control from Pakistan. Authorities have been able to track his phone calls back to London and wire transfers of money intended to pay for the suicide bombers’ plane tickets. The suspected terrorists had planned to be on flights out of London today and tomorrow for a dry run of their plot had the plot not been disrupted. U.S. authorities said today they’re keeping their guard up in case of follow-on or copycat terrorists. "There are other people out there who are terrorists or terrorist sympathizers, so I’m not prepared to let my guard down," said Michael Chertoff, Secretary of the Department of Homeland Security. U.S. law enforcement sources tell ABC News more than 200 FBI agents have been searching for people connected to the plot here in the U.S. With nothing found, so far at least, according to White House Homeland Security Advisor Fran Townsend on Good Morning America this morning. "There is no indication of plotting, but of course we would be remiss if we weren’t looking for connections between individuals here in the U.S. and the plotters in the U.K.," Townsend said. "There are leads that the FBI is running." In Pakistan today, officials took credit for breaking the case through the surveillance of the one of the suspected plotters who reportedly met with a radical cleric. Pakistani authorities said they had arrested the suspect, Rashid Rauf, on Wednesday in cooperation with British authorities. They said he was found near the border with Afghanistan and had direct ties to al Qaeda. "They are saying that the cell that they dismantled here was very close to al Qaeda, was linked to al Qaeda," Alexis Debate, Senior Fellow at the Nixon Center in Washington, D.C. and ABC News consultant, said. Despite a whirlwind of raids and arrests, the five missing suspects in London remain at large. And U.S. officials confirm that one of the suspects was a Heathrow airport employee with an access pass that gives him the run of the airport.