The United States Secret Service has been alerted in response to a tweet by actor Peter Fonda, who said Barron Trump -- President Donald Trump's youngest son -- should be separated from his mother and put "in a cage with pedophiles."
"We should rip Barron Trump from his mother's arms and put him in a cage with pedophiles and see if mother will will stand up against the giant a--hole she is married to. 90 million people in the streets on the same weekend in the country. F---," Fonda wrote in a tweet, which has since been deleted.
First lady Melania Trump's communications director, Stephanie Grisham, called the tweet "sick and irresponsible," adding that the Secret Service has been notified. A Secret Service spokesman said the agency is aware of the tweet but declined to comment, citing the agency's practice of not speaking about protective matters.
The President's eldest son, Donald Trump Jr., weighed in on Twitter as well.
"You're clearly a sick individual and everyone is an internet bada-- but rather than attack an 11 year old like a bully and a coward why don't you pick on someone a bit bigger. LMK," Trump Jr. tweeted, using the shorthand Internet term for "let me know."
The tweets come as the Trump administration has faced heightened pressure over its US immigration policies, which in some instances have resulted in the separation of undocumented children from their families.
Fonda later apologized for his tweet.
"I tweeted something highly inappropriate and vulgar about the president and his family in response to the devastating images I was seeing on television," he said in a statement. "Like many Americans, I am very impassioned and distraught over the situation with children separated from their families at the border, but I went way too far. It was wrong and I should not have done it. I immediately regretted it and sincerely apologize to the family for what I said and any hurt my words have caused."
On Wednesday, the President said he would take "pre-emptive" action soon while members of Congress work to address the situation. He later signed an executive order declaring it is his administration's policy to "maintain family unity," including by detaining entire families together "where appropriate and consistent with law and available resources."