By Frank McGurty

(Reuters) - The chief of the Dallas Police Department on Sunday vigorously defended the use of a bomb mounted on a robot to kill a gunman who shot to death five officers during a march to protest police violence against blacks.

In taking personal responsibility for approving the plan in the aftermath of Thursday's shootings, Chief David Brown said he was convinced that any hesitation in giving the go-ahead would have allowed the gunman the chance to harm other officers.

"I approved it and would do it again if presented with same circumstances," Brown told CNN, referring to the strategy of deploying a bomb-equipped robot into a room where the suspect was holed up after his shooting rampage.

That strategy revived the debate over the militarization of U.S. law enforcement. Police were sharply criticized in 2014 after deploying military-style guns and armor to quell protests against the killing of an unarmed black teenager in Ferguson, Missouri.

After two hours of fruitless negotiations with the Dallas gunman, Brown asked senior officers to "use their imaginations" to devise a strategy to disable the shooter, later identified as Micah Xavier Johnson, 25, a former U.S. Army Reserve soldier who authorities said embraced black nationalism.

"He seemed very much in control and very determined to hurt other officers," said the police chief, who revealed that Johnson taunted negotiators and asked them how many officers he had shot. "Without our actions, he would have, he would have hurt more officers."

Brown said he stood by his decision but understood why questions have been raised about the use of deadly force against the gunman, rather than opting for a non-lethal method to disable him.

"I appreciate critics but they are not on the ground. And their lives are not at risk," Brown said.

While stopping short of directly criticizing the decision, New York City Police Commissioner Bill Bratton on Sunday said a broad policy discussion should take place before law enforcement resorts to such tactics on a regular basis.

"It is something that needs to be done in a very public way," Bratton said on ABC's "This Week" program. "It is the first time that type of action has been initiated here in the United States and it deserves to be reviewed."

U.S. law enforcement has used remotely controlled devices before to help stop suspects but not to kill anyone, experts say. Such devices are often used by police to dispose of or detonate bombs without risking human life.

A year ago, President Barack Obama banned police departments from using certain military hardware and restricted the use of riot shields and other equipment.

Obama said the ban would encourage trust-building between police and the communities they serve.

(Reporting by Frank McGurty in New York; Editing by Andrew Roche and Paul Simao)