Washington (CNN) Actor Johnny Depp on Thursday became the latest US celebrity to invite controversy by making a thinly veiled allusion to the killing of President Donald Trump, asking the crowd at the Glastonbury arts festival in England, "When was the last time an actor assassinated a president?"

The comments, interpreted as a nod to the assassination of President Abraham Lincoln by John Wilkes Booth more than 150 years ago, sparked widespread condemnation.

But it's clear the US has opened a new chapter in the debate over political expression, art and inciting violence against public figures, one that has been raging for years but has taken on a heightened pitch since Trump took office -- and a slew of celebrities have lined up to oppose him with increasingly provocative language.

Depp apologized in a written statement first reported by People Magazine for the "bad joke" he made, calling it "in poor taste."

"It did not come out as intended, and I intended no malice. I was only trying to amuse, not to harm anyone," he said in the statement.

The comments, abhorrent and offensive in any context, come at a sensitive time in terms of violence and political discourse, just eight days after a gunman opened fire on members of Congress at an Alexandria, Virginia, baseball field where they were practicing for a charity baseball game. That shooting injured Republican Steve Scalise, the majority whip of the House of Representatives, who remains hospitalized.

As Depp predicted at Glastonbury, the comment indeed made headlines and the White House did not appear to find it funny.

White House press secretary Sean Spicer suggested that there was a double standard about threats of violence toward Trump.

"It's a little troubling, the lack of outrage that we've seen in some of these instances where people have said what they've said with respect to the President, and the action that should be taken," Spicer told reporters at an off-camera briefing. "The President's made it clear that we should denounce violence in all its forms, and I think if we're going to hold to that standard and we should all agree that standard should be universally called out."

Deputy White House press secretary Sarah Huckabee Sanders called on Depp's colleagues "to speak out against this type of rhetoric as strongly as they would if his comments were directed to a Democrat elected official."

Republican National Committee Chairwoman Ronna Romney McDaniel said that "no joke" about killing the President is acceptable.

"I'm sick of celebrities getting away with such disgusting comments," she wrote on Twitter.

To McDaniel's point, Depp is not the first celebrity to allude to --- whether in jest or in earnest -- the killing of President Trump. He's also not the first to follow it up with a mea culpa or explanation after the fact.

In May, the comic Kathy Griffin came under sharp fire after posing for photos holding a mask styled to look like the bloodied head of the President. She was fired by CNN from her role as co-host of the network's annual New Year's Eve program, and the President himself weighed in, saying that Griffin should be "ashamed of herself."

"My children, especially my 11 year-old son, Barron, are having a hard time with this," Trump wrote on Twitter. "Sick!"

And at January's Women's March on Washington, pop icon Madonna mused in a speech that she'd "thought an awful lot about blowing up the White House," a statement that she later said was taken "wildly out of context."

Outrage also mounted over a production of Shakesepare's "Julius Caesar" at New York's Public Theater, in which the depiction of the titular character bore resemblance to Trump. Sponsors, including Delta Airlines and Bank of America, pulled their support from the production and protests objecting to the portrayal interrupted the play.

These incidents are hardly the only instances in which Hollywood's biggest stars have stepped out to critique the Trump administration and the President's policies. Meryl Streep, who campaigned for Hillary Clinton, characterized Trump as a bully who disrespects others during a speech at the Golden Globes. Alec Baldwin has portrayed Trump unkindly on "Saturday Night Live" and Jimmy Kimmel, while hosting the Oscars, made several cracks at Trump's expense.

Trump is not the only president to have been the target of celebrity fury -- and even threatening comments similar to the ones Depp made on Thursday. In the run-up to the 2012 election, the rock guitarist and conservative provocateur Ted Nugent said that if Obama was re-elected, he himself would either be "dead or in jail," a comment that earned him a visit from the Secret Service

Trump himself has been criticized for making comments that have appeared to advocate violence against others, including those on the other side of the political aisle. During the 2016 presidential campaign, Trump appeared to encourage gun owners to take some form of action if Hillary Clinton was elected and appointed judges who do not support gun rights.

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He also declined to rebuke an adviser for suggesting that his 2016 opponent should be "shot for treason," a suggestion made by Al Baldasaro, who informally advised Trump on veterans issues.

"This whole thing disgusts me -- Hillary Clinton should be put in the firing line and shot for treason," Baldasaro said referring to Clinton's actions during the attack on the US mission in Benghazi.

Asked about Baldasaro, who coincidentally was at the White House on Friday for a bill signing, Spicer did not appear to remember the comments.

"I don't believe -- and the President has said this as well -- anybody who goes out and tries to highlight those kinds of actions should not be welcome," Spicer told reporters in the off-camera briefing. "I'm not aware of the comments he made. I don't think that we should be resorting to that language with respect to anyone in our country."

Whether the President will take his press secretary's response to heart remains unclear.