Washington (CNN) The Killers cover political topics from the border wall to mass incarceration on their new song "Land of the Free."

Lead singer Brandon Flowers said in a note posted to Instagram that the idea for the song began after the Sandy Hook shooting in 2012.

"In the months and years that followed, America would be hit with an onslaught of more mass shootings of innocents and too many examples of racial injustice to ignore," he wrote.

Flowers credited Ava DuVernay's "13th," a film about race and incarceration, and Jimmy Kimmel's political monologues with convincing him to turn his thoughts into music. He also mentioned his grandmother, a Lithuanian immigrant who traveled to the US to escape Soviet oppression, and said, "We dishonor our values, our ancestors and our heritage when we tear gas our brothers and sisters seeking asylum."

"I love my country," Flowers wrote. "I know that these are complicated issues but whether you stand to the left, right, or straddle the line, you've gotta believe that we can do better."

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