HARTFORD, Conn. — Last week’s landmark U.S. Supreme Court ruling that upheld a constitutional right to own guns for self-defense and hunting may harm efforts to deter violent crime in communities and college campuses, the FBI Director, Robert Mueller, said today.

Speaking at a convention of the International Association of Campus Law Enforcement Administrators at Hartford, Mr. Mueller criticized the ruling, which he said “does throw a lot of things up in the air.”

Last year, a gunman killed 32 people at Virginia Tech in the nation’s worst mass shooting in modern history, prompting some states to consider new laws to tighten campus security. Earlier this year, a gunman killed five people at Northern Illinois University.

By a 5-4 vote last week, the nation’s highest court struck down the District of Columbia’s 32-year-old ban on handguns, the first major pronouncement on gun rights in history. It upheld the right for communities to license guns.

Mr. Mueller said communities will have to determine their own license programs. As a former Marine who served in Vietnam, he said “I tend to believe weapons harm people and more often than not they harm the people carrying them.”

With his grandchildren going to college, Mr. Mueller said he hopes “those campuses will be weapons free.”

Mr. Mueller said the FBI’s top priority remains counterterrorism, counter-intelligence, and protecting the secrets of America.

He said college campuses and small communities could be “potential incubators of terrorism” even while major cities such as New York and Los Angeles remain primary targets for terrorists.

“The fact is we can’t rule out any community in the United States as a potential incubator of terrorism,” Mr. Mueller said.