SEATTLE, July 22 - Inside a former Starbucks warehouse, this city's bomb squad headquarters, the police chief and 15 captains and sergeants - accompanied by a robot that can extract explosives from packages and pin down a suspect - huddled the other day to tackle a topic suddenly urgent to the police across the nation: suicide bombers.

"Now it's really time," the chief, Gil Kerlikowske, told his commanders. "It almost seems to be a question of when in this country, not a question of if, after London."

Across the country, police departments large and small are preparing for a possibility once thought improbable and now feared to be inevitable. On Thursday, the day of four attempted explosions in the London subways, the New York City police began randomly searching bags and backpacks at subway stations and other travel hubs.

In Miami, the police chief returned recently from a conference in England and Scotland that included a long session on suicide bombers. Several officers with the Los Angeles County Sheriff's Department returned last Thursday after spending a week with the British authorities studying terrorism responses, department officials there said.

A growing number of police departments, including ones in Seattle; Boston; Los Angeles; Washington; Suffolk County, N.Y.; and Sterling Heights, Mich., a small city north of Detroit, are also turning for guidance to the place many police officials consider the pinnacle of terrorism training. They are sending groups of officers to Israel and bringing Israeli officers to the United States to train the police on the harrowing science of suicide bomber intelligence gathering and apprehension.

Several American police officials said advice from the Israelis had included looking out for suicide bomber "handlers," who scout bus stations or other crowded areas for deadly attacks. And although the police are typically told to aim for the chest when shooting because it is the largest target, the Israelis are teaching officers to aim for a suspect's head so as not to detonate any explosives that might be strapped to his torso.

But the growing relationship between Israeli and United States law enforcement, expanding now after the London bombings, has prompted criticism among some Muslim groups, who say they fear that American police officers will engage in religious or ethnic profiling.

Some officials talk about receiving reports from the public about what the police refer to as "M.E.W.C.'s" - Middle Eastern with a camera - perhaps taking pictures of a bridge, a hydropower plant or a reservoir.

"Israel's antiterror tactics are largely based on profiling, whether it's on airlines or at checkpoints," said Ibrahim Hooper, a spokesman for the Council on American-Islamic Relations, based in Washington. "And they've produced tremendous resentment and hostility in the Palestinian population through humiliating tactics and through abuses on a daily basis. And I don't think that's something we want to replicate."

But Chief Kerlikowske said that the focus of the work with Israelis - an Israeli police general based at the Israeli Embassy in Washington is expected to come here for training next month - was on technical skills, and that the police were focusing on the behavior of potential bombers, not on race or religion.

"None of the discussions I've heard have to do with profiling," Chief Kerlikowske said.

In the last week, officials in Seattle - not far from where an Algerian man, Ahmed Ressam, was arrested in 1999 trying to enter the country with explosives to be used at the Los Angeles airport during the millennium celebration - have proposed ways to train officers with a three-part "lesson plan" for detecting and stopping suicide bombers. Some police officials, however, acknowledge that many of the roughly 18,000 American police departments and federal law enforcement agencies lack access to centralized training for response to such attacks and say that the biggest weakness lies in intelligence gathering on extremists.

The National Bomb Squad Commanders Advisory Board, which works with more than 450 bomb squad units, is drafting the first national protocol for "suicide bomber response," to be distributed to all the units in September, said Sgt. Jim Hansen of the Seattle Police Department's arson bomb squad and a member of the organization's board.

Inside the warehouse here, the Seattle police officials talked about how they would get the word out to their roughly 1,250 officers - whether through a video or special training - to help them see signs of a potential attack: gunpowder, a suspicious backpack, a suspect sweating profusely. They spoke about the "nine steps" a suicide bomber takes, but were reluctant to share the details with a reporter for fear of tipping off would-be bombers, they said.

Many police and federal officials have gone to Israel through a program organized by the Jewish Institute for National Security Affairs, a nonprofit group in Washington that promotes close ties between the United States and the Israeli military and the police. Marsha Halteman, director of corporate and community programs for the institute, said that it got its money from private donors and that it had been sponsoring such trips for American officers since 2002.

Since the London bombings of July 7, Ms. Halteman said, interest in cooperation between the countries' police agencies has increased considerably. The institute pays the cost of the trips to Israel, roughly $6,500 for each state or local officer; it does not pay for federal officers' expenses, Ms. Halteman said. Since 2002, the institute has sent dozens of American law enforcement officials to Israel and sponsored several conferences here with Israeli security experts. An itinerary for a recent institute-sponsored trip to Israel listed among the lessons "The Mind-Set of the Suicide Bomber," "Security Technology" and "Enlisting the Public in the Fight Against Terrorism."

Barnett Jones, chief of the Sterling, Mich., Police Department, with 259 employees, was one of more than a dozen officials who went to Israel for training in April.

"One would say it is the front line," Chief Barnett said of Israel. "We're in a global war."

Asked whether he had specific concerns because of the large Arab and Muslim population in the Detroit area, he responded delicately, saying: "The reality is we have a large population in our community that immediately become suspect, whether that is right or wrong, because of the global war. For me to sit here and say, 'I'm not concerned' would be wrong, but for me to sit here and say, 'Yes I'm concerned' would also be wrong."

The New York City Police Department has worked with the Israelis since soon after the Sept. 11 terrorist attacks and has permanently stationed a Hebrew-speaking detective in Israel, who returns to the city often to train other officers. Since the July 7 London bombings, the department, which has an annual budget of $2 billion, has spent an additional $2 million a week, primarily on mass transit security, said Paul J. Browne, the deputy commissioner for public information. He said he did not expect that the new policy of searching backpacks and packages would add significantly to the cost.

Chief Kerlikowske of the Seattle police, which pays its own way for trips to Israel, said his department, with an annual budget of $182 million, would spend up to $30,000 for additional training on suicide bomber response. Some expensive items like the robot and a portable X-ray machine using digital film have been paid for with money from the Department of Homeland Security.

The X-ray machine was used last month when a man upset about his case entered the federal courthouse in Seattle with a backpack strapped to his chest and a grenade in his hand. Officers shot him in the head and killed him; the X-ray machine was used to examine his backpack, which turned out to have only a cutting board inside. The grenade was determined to be inactive.

Even as more police departments seek suicide-bomber training, several officials said the police in the United States had challenges that did not exist in other countries.

"Here we don't have a centralized department, and the biggest obstacle is sharing information, working at local, state and then the overlay with the feds," Chief John F. Timoney of Miami said. "If you were George Bush, and you went to Harvard and asked them to design a policing scheme, the last one they would dream up is the American policing scheme; it's completely dysfunctional. We've got to do a much better job on intelligence."

"I think now suddenly, what we are seeing is that it's really happening," said Brig. Gen. Simon Perry of the Israel National Police, now based at the Israeli Embassy in Washington and one of several Israeli security experts traveling around the nation to conduct training sessions for American law enforcement.

"I think for terrorist attacks, you need two things: you need a capability, and you need a motivation," he said. "The capability is here, and the question now is motivation."

Suicide Bombings Bring Urgency to Police in U.S.