"Ninety million people in the streets on the same weekend in the country. F-".
Donald Trump Jr., meanwhile, did some tweeting of his own, addressing Fonda: "You're clearly a sick individual" who behaved "like a bully and a coward".
In his earlier tweetstorm the Easy Rider actor also said "we should hack the system" and "get the addresses of ICE agents" to "surround their homes" and "find out what schools their children go to and surround the schools".
Moreover, The Wrap reports that "Melania Trump's spokesperson was quick to denounce Fonda: 'The tweet is sick and irresponsible and USSS has been notified.'" The outlet added, "the U.S. Secret Service told TheWrap that is aware of the tweet but declined to offer any additional comments".
Peter Fonda's vitriol toward Trump is over the policy that has separated over 2,000 babies and children from migrant families crossing the U.S. border illegally, with some seeking asylum.
Fox News reported that Frank Sinatra's daughter, Nancy, tweeted support for Fonda, telling him to "say how you really feel, blues baby". "I immediately regretted it and sincerely apologise to the family for what I said and any hurt my words have caused". They are more interested in calling for violence against women and children.
After some since-deleted tweets the 78-year-old Oscar-winner made about the Trump Administration's policy of separating children from their families at the southern border gained negative attention and were flagged by the Secret Service, he's issued an apology and brief explanation for his rhetoric. Other tweets used vulgar terms to describe Homeland Security Secretary Kirstjen Nielsen and White House press secretary Sarah Huckabee Sanders.