Donald Trump Jr. thanked Chelsea Clinton Thursday for coming to the defense of Barron Trump after a comedian posted a joke about his younger half-brother on social media.

"On this we agree. Thank you," Donald Trump Jr., President Trump's eldest son, wrote on Twitter in response to an earlier tweet by Clinton.

Clinton on Tuesday issued a stinging rebuke of Zack Bornstein, a former "Saturday Night Live" and "Jimmy Kimmel Live!" writer, following a joke he made in a now-deleted tweet that Barron Trump had been "recast" as first lady Melania Trump's State of the Union guest, Preston Sharp.

"Whatever our politics, I hope we can agree to both leave 11-year old private citizen Barron Trump alone and celebrate 12-year old Preston Sharp for his work to honor the graves of every military veteran," Clinton wrote.

Sharp was invited to President Trump's inaugural State of the Union address Tuesday to highlight his campaign, which is raising money for American flags and flowers that can be laid at the graves of fallen service personnel.

This is not the first time Clinton, daughter of former President Bill Clinton and 2016 Democratic presidential nominee Hillary Clinton, has stood up for first children.

She previously condemned news outlets for their coverage of Barron Trump, President Trump's only child with Melania Trump, in August after an opinion piece was published criticizing the way he dressed.

She has also censured reporters for tabloid stories written about former President Barack Obama's eldest daughter Malia Obama, who started at Harvard University in 2017 since leaving the White House.