The new deputy commissioner for counterterrorism at the New York Police Department, Richard Falkenrath, is one of the people responsible for keeping 8 million New Yorkers safe.

It’s a stressful job. Mr. Falkenrath said that when he wakes up every morning at 6:20 a.m. and heads into the office for his 9 a.m. meeting with Police Commissioner Raymond Kelly and the deputy commissioner for intelligence, the CIA veteran David Cohen, he assumes “today is going to be the day.”

By that, he means today is going to be the day that extremist Islamist terrorists attempt to hit New York with a nuclear, chemical, biological, or even a conventional attack aimed at inflicting at least dozens, maybe even tens of thousands, of casualties on New York City.

“If I had to pick one area where we are most likely to get hit, I think it is the subways,” Mr. Falkenrath said in an exclusive interview with The New York Sun, his first sit-down since starting on the job in New York on July 10. “It’s a target for Al Qaeda.”

Mr. Falkenrath, 37, is the most recent in a string of prize recruits that Mr. Kelly has been able to lure back to public service after the September 11, 2001, terror attacks. Mr. Cohen, a 35-year veteran of the CIA who, unusually, served as both deputy director of intelligence and deputy director of operations (and as a confidante of the new nominee to be secretary of defense, Robert Gates), left a comfortable berth at AIG to become the NYPD’s deputy commissioner for intelligence.

NYU’s general counsel, Andrew Schaffer, became the NYPD’s deputy commissioner for legal matters. Another legal talent, Martin Karopkin, a former New York Supreme Court justice, recently became the NYPD’s deputy commissioner for trials.

Upon returning to the NYPD in 2002, Mr. Kelly called IBM’s CEO, Louis Gerstner, to recommend someone to revamp the NYPD’s ailing information technology office, and landed James Onalfo, a former Kraft Foods, Stanley Works, and Perot Systems CIO, to bring Fortune 500 IT experience to Police Plaza.

Mr. Falkenrath said that when Commissioner Kelly telephoned him with a job offer, he felt like he could be knocked over with a feather.

Even in a job that might give a lot of people sleepless nights, Mr. Falkenrath seems able to take mental time-outs. The screen saver on his computer is a shot of the house he grew up in, perched in the woods of Northern California. He slept there, he said, with a double-barreled 12-gage shotgun next to his bed for when the quail got in the vegetable garden.

Ask him for his phone number, and he begins with “202” before catching himself. He spent the last few years in Washington, serving as an aide on the National Security Council, deputy homeland security adviser, a fellow at the Brookings Institution, and even as a spokesman for the Bush-Cheney reelection campaign. Before coming to Washington, he worked for seven years at Harvard’s Kennedy School of Government.

As head of the counterterrorism bureau, Mr. Falkenrath supervises more than 100 NYPD detectives assigned to the Joint Terrorism Task Force, a cooperative venture between the NYPD and the FBI. He has a series of counterterrorism inspectors, senior NYPD officials “embedded” in major commands within the police department to put a priority on counterterrorism. He runs counterterrorism training for the whole NYPD; a “special projects” team that probes for vulnerabilities; a “shield” group that works with businesses to protect their facilities, and a weapons of mass destruction unit that has deployed sensor systems throughout the city to detect an unconventional attack.

Mr. Falkenrath said that when he first met as a White House official with his predecessor in the NYPD counterterrorism post, another former White House aide, Michael Sheehan, and with Mr. Cohen, he was “blown away” by the extent of the police department’s programs.

“There is nothing like it in the country,” he said.

Mr. Falkenrath said New York faces the threat of both domestic “homegrown” terror plots, like the Herald Square attack prevented by the NYPD and prosecuted at the federal level, and internationally-planned plots such as the attacks of September 11.

“We have the most information about the international plotting,” he said. But that doesn’t mean it can be the sole focus. “You can’t be like the drunk looking for his wallet under the lamp post,” he said.

Mr. Falkenrath’s Washington experience has supplied him with a series of ideas about how the federal government can help cities such as New York protect themselves, and he wants to expand the counterterrorism bureau with some new staff specializing in policy.

“We would like to see the federal government regulate ammonium nitrate,” he said, referring to the fertilizer used to make the bomb that leveled the federal building in Oklahoma City. He mentions that the federal Bureau of Alcohol, Tobacco and Firearms has reported 350 thefts of regulated high-grade explosives since 2000, and suggests security be stepped up at construction sites. Cumbersome regulations affecting domestic counterterrorism investigations could be streamlined. “I want to get these things changed,” Mr. Falkenrath said.

Asked whether the checkpoints the police have set up at subway entrances have caught any would-be bombers, Mr. Falkenrath said, “The statistic I care most about is ‘zero.'”

In the counterterrorism business, success isn’t finding the ticking bomb in the satchel in the subway — success is “no ticking bomb in the subway.”

The subway checkpoints have been challenged in court, so far without success, by the New York Civil Liberties Union. After a court upheld the searches, the tactic was adopted in the Boston subway system.

Would a hasty American withdrawal from Iraq hurt New York’s security? “Mostly indirectly. It’s complicated,” Mr. Falkenrath replies. “If we withdraw and the country collapses, it can become another training ground, a failed state awash in weapons and explosives.”

New York’s vulnerabilities include not only the subway system but also the presence of foreign missions of enemy countries. The police department’s deputy commissioner for public information, Paul Browne, who accompanied Mr. Falkenrath to the interview at the Sun, noted that since September 11, 2001, six Iranian government employees assigned to the Iranian U.N. mission in New York had been caught casing the New York subway system, in three incidents, each involving two diplomats. The diplomats were seen by the FBI and NYPD and expelled from America.

The bottom line for ordinary New Yorkers? “We are high if not at the top of Al Qaeda’s target list, but have a very robust effort” to counter an attempted attack,” Mr. Falkenrath said. “People should go about their lives without constant fear.”