Movie legend Robert De Niro's beef with Donald Trump goes back long before the GOP presidential nominee formally entered the political arena in 2015. 

However it's fair to say that since the 2016 election, De Niro has stepped up the war of words, from calling Trump a 'monster with no redeemable qualities' to speaking of his fantasy of seeing a bag feces thrown in the face of the 45th president.

The feud returned to the headlines this week when De Niro showed up outside of Trump's criminal trial in Manhattan. Earlier this month, The Godfather II star narrated a Joe Biden-campaign video that took aim at Trump's policies. 

'I don't mean to scare you. No, wait, maybe I do mean to scare you. If Trump returns to the White House, you can kiss these freedoms goodbye that we all take for granted,' De Niro told reporters on Tuesday. 

The actor cast himself as the true New Yorker and mocked Trump's history of sometimes-unsuccessful business ventures and self-promotion, saying Trump was looking to 'destroy' the city. 

Former President Donald Trump gave a review of Robert De Niro's performance outside of his hush money case overnight Wednesday on his Truth Social website 

De Niro pictured with his girlfriend, Tiffany Chen, at the White House in April 

Back in 2008, De Niro actively campaigned for President Barack Obama's campaign and continued to back his leadership after the Illinois' Democrat's landslide victory. 

In 2011, Trump began to claim that Obama was not born in the United States, making never-proven claims about things that his 'investigators' had discovered and alleging that the president was a Muslim. 

During an interview at the Tribeca Film Festival in April 2011, De Niro appears to have taken his first shot at Trump, who was then most famous as the host of The Apprentice. 

'I won't mention names, but certain people in the news the last couple weeks, just, what are they doing? It's crazy. They're making statements about people that they don't even back up. Go get the facts before you start saying things about people.'

When pressed, DeNiro confirmed he was speaking about Trump. 

'It's like a big hustle; It's like being a car salesman. Don't go out there and say things unless you can back them up. How dare you? That's awful to do. To just go out and speak and say these terrible things? Unless you just wanna get over and get the job. It's crazy.'

True to character, Trump did not take those comments lying down and hit back during a phone interview with Fox & Friends. 

'I like his acting, but in terms of when I watch him doing interviews and various other things, we're not dealing with Albert Einstein.' He went on to call De Niro: 'Not the brightest bulb on the planet.'

Donald Trump's Twitter response to De Niro, sent while the former Apprentice host was in the Oval Office

 The two locked horns again in the run-up to the 2016 election when De Niro hit the campaign trail for Hillary Clinton. In one video, he issued a full throated condemnation of Trump's policies and rhetoric. 

'He's so blatantly stupid. He's a punk, he's a dog, he's a pig [...] a mutt who [...] doesn't do his homework, doesn't care. He's an idiot. Colin Powell said it best: He's a national disaster. He's an embarrassment to this country.'

'It makes me so angry that this country has gotten to this point that this fool, this bozo, has wound up where he has. He talks how he wants to punch people in the face? Well, I'd like to punch him in the face.'

The same year, De Niro compared Trump's popularity to the to the positive coverage that his psychotic killer character Travis Bickle receives at the conclusion of Taxi Driver. 

Shortly after Trump won his shock and controversial election victory, De Niro appeared on Jimmy Kimmel Live where the comedian asked the Goodfellas star if he would still punch the then president-elect. 

'I can't do that now he's president. And I have to respect that position … I just have to see what he's going to do and how he's going to follow through on certain things.' 

That apparent détente did not last very long. 

Trump speaking in 2011 at the height of his failed attempt to prove that President Barack Obama was not born in the US 

In March 2017, De Niro criticized the Trump administration's cuts for arts programs. 

'For their own divisive political purposes, the administration suggests that the money for these all-inclusive programs goes to rich liberal elites. This is what they call an "alternative fact." I call it what it is - bulls***,' De Niro said, according to CNN.

De Niro upped the ante in 2018 at the Tony Awards where he declared: 'F*** Trump!'

That same year, at different points, he called Trump a 'mad man,' a 'low life,' 'f*****g idiot,' 'baby-in-chief' and 'jerkoff-in-chief.' 

In an interview on The Late Show with Stephen Colbert in 2019 De Niro compared the Trump presidency to 'living in an abusive household' called him a 'deep fake president.'

The barbs have not been all one way traffic either.

While in the Oval Office, Trump took the time to snap back at De Niro. 

'Robert De Niro, a very Low IQ individual, has received [too] many shots to the head by real boxers in movies. I watched him last night and truly believe he may be "punch-drunk."'

'I guess he doesn’t realize the economy is the best it’s ever been with employment being at an all time high, and many companies pouring back into our country. Wake up Punchy!'

The war between the two Big Apple natives will not let up. 

On Tuesday, Trump’s campaign staffers held their own news conference at the same spot outside the courthouse to respond to De Niro and the Biden campaign. 

Trump’s senior campaign adviser, Jason Miller, called De Niro — who won Oscars for his roles in The Godfather: Part II and Raging Bull — a washed-up actor and said the Biden news conference proved Trump’s arguments that the trial, like the others the former president is facing, was motivated by politics.

'After months of saying politics had nothing to do with this trial, they showed up and made a campaign event out of a lower Manhattan trial day for President Trump,' Miller said.

Karoline Leavitt, the Trump campaign’s press secretary, called the Biden campaign 'desperate and failing' and 'pathetic' and said its event outside the trial was 'a full-blown concession that this trial is a witch hunt that comes from the top.'

Even Trump responded to De Niro's Tuesday appearance.  

'I never knew how small, both mentally and physically, Wacko Former Actor Robert De Niro was,' the ex-president said about the 5-foot-10 star.

The presumptive Republican nominee accused De Niro of suffering 'from an incurable case of TRUMP DERANGEMENT SYNDROME' and said the actor was met 'with a force greater than the Radical Left - MAGA.'