Neil Young's song, 'Keep On Rockin' In The Free World', is exactly the kind of crowd-favourite, boomer-friendly rock that Donald Trump deploys at his rallies.

It's usually followed up by something like Twisted Sister's 'We're Not Going To Take It Anymore' or even Lee Greenwood's 'God Bless The USA', but the reality is that there's a laundry list of musicians who have openly rejected Donald Trump and told him to stop using his music.

Neil Young, however, has gone one step further. After recently becoming a US citizen, the 'Heart of Gold' singer took it upon himself to pen an open letter to the President of his new country, and put the man on blast.

"You are a disgrace to my country," Young's open letter begins. "Our first black president was a better man than you are."

Young takes Trump to task about his terrible record on climate change, bragging about the economy for which he had no part in, and targeted his golf courses in the letter too. "Every time 'Keep On Rockin' In The Free World' or one of my songs is played at your rallies, I hope you hear my voice. Remember it is the voice of a tax-paying citizen who does not support you."

Young ended his letter by endorsing Bernie Sanders, saying that while his initials are 'BS', his policies aren't.

You can read Neil Young's full letter here.