Donald Trump is still locked in a new front in his long campaign of cultural combat – a rolling war against some of the world's biggest pop stars, whose music he borrows for his own political ends while publicly deriding them when they push back. As RadarOnline.com readers know, the US president, 80, is now waging war in Iran and threatening invasions of Canada, Greenland, Cuba, Colombia and Panama, and has also ordered strikes in Syria, Somalia, Iraq, Yemen and Nigeria. But some of his most personal battles have played out not on foreign soil but in the glare of the entertainment world, as he clashes with Katy Perry, Taylor Swift, Bruce Springsteen, Madonna, Beyoncé – and a long list of other musicians who have denounced his policies or blocked him from using their songs.