The former Obama administration official told Martha Raddatz on ABC's "This Week" that Confederate monuments have become "rallying points" for white nationalists and neo-Nazis.
"I salute those in cities and states taking down monuments for reasons of public safety and security," Johnson said. "That's not a matter of political correctness. It's a matter of public safety and homeland security and doing what's right."
The issue of removing memorials to the Confederacy came to a head last weekend in Charlottesville, Virginia, when a white supremacist rally to protest the city's decision to take down a statue
of Gen. Robert E. Lee exploded in violence
, leaving a counterprotester, Heather Heyer, dead and dozens injured. Two state troopers, H. Jay Cullen and Berke Bates
, were also killed when their helicopter crashed while they were helping the city respond to the violence.
Some Confederate monuments have been taken down or vandalized since the deadly violence, and groups are demanding the removal of others
President Donald Trump said last week that the removal of such monuments is "foolish" and said such actions are ripping apart the "history and culture of our great country."
Johnson also addressed the recent departures of several top White House aides. He said the current and former military generals that Trump has on his team, including chief of staff John Kelly, Defense Secretary James Mattis and national security adviser H.R. McMaster, should stay put and perform their duties.
"Frankly, if John Kelly or my friend Jim Mattis came to me and said I'm thinking about resigning from this White House, I'd say absolutely not. You have to stay," Johnson told Raddatz. "As John reportedly said, it's country first. And we need people like John Kelly, Jim Mattis, H.R. McMaster to right the ship."
Over the past several weeks, the White House has seen several high-profile departures, including chief White House strategist Steve Bannon
, press secretary Sean Spicer
, chief of staff Reince Priebus
, communications director Anthony Scaramucci
and press aide Michael Short