WASHINGTON — The Black Lives Matter movement is creating an environment that can put police officers at risk, Republican presidential candidate Chris Christie said Sunday, accusing President Barack Obama of supporting the movement, encouraging “lawlessness” and not backing up law enforcement.

“I don’t believe that movement should be justified when they are calling for the murder of police officers,” Christie said on CBS’ Face the Nation. Told that some individual members have been recorded calling for the deaths of   officers, Christie replied that the environment is “what the movement is creating.”

Black Lives Matter was established after the 2012 shooting of Trayvon Martin, an unarmed teen, by a neighborhood watch enthusiast, and has become an issue in the 2016 presidential campaign. The group said on its Facebook page in September that conservatives are trying to turn the movement into a danger to officers.

“We’re targeting the brutal system of policing, not individual police,” the movement said in its statement. “The Black Lives Matter Network seeks to end the system of policing that allows for unchecked violence against black people.”

Police groups have bristled at that comment and pointed out people in marches who were recorded chanting for the deaths of police officers. During a protest outside Minnesota’s state fair this summer, for example, some marchers were recorded chanting to fry police “like bacon.” Earlier this month, the parents of slain black men and women were featured speakers at the “Justice or Else” march marking the 20-year anniversary of the Million Man March in Washington.

President Barack Obama last week defended the Black Lives Matter movement, noting protests are giving voice to a problem happening only in African-American communities.

“We, as a society, particularly given our history, have to take this seriously,” Obama said.

The movement has become an issue in the presidential campaign. Some have taken its name as an implication that other people’s lives don’t matter, and respond by saying, “All lives matter.”

Democratic presidential hopeful Martin O’Malley initially took that tack but apologized last summer. At the Democratic presidential debate earlier this month, he joined the party’s other presidential hopefuls in giving a nod to the movement. African-Americans overwhelmingly vote for Democrats.

“Black lives matter, and we have a lot of work to do to reform our criminal justice system, and to address race relations in our country,” O’Malley said.