Neil Young and Donald Trump are at odds over Trump's use of Young's track "Rockin' In the Free World."

It all started when Trump used the track as part of the announcement that he was running for president.

"Donald Trump was not authorized to use 'Rockin' in the Free World' in his presidential candidacy announcement," a spokesperson for the rocker's Lookout Management said in a statement.

"Neil Young, a Canadian citizen, is a supporter of Bernie Sanders for President of the United States of America."

However, Trump's camp says they used the song legally.

"Through a license agreement with performance-rights organization ASCAP, Mr. Trump's campaign paid for and obtained the legal right to use Neil Young's recording of 'Rockin' in the Free World' at today's event,".

"Mr. Trump is a huge fan of Neil Young and his music and will continue to be regardless of Neil's political views."