In what became a trifecta of attacks involving Barnett Newman works a 29 year old veterinary student attacked Who's Afraid of Red, Yellow and Blue IV with one of the bars used to keep visitors at a distance.
He "began by hitting the painting with one of the plastic bars used to keep visitors at a distance. He then placed several documents on and around the damaged work: on its blue part, a slip of paper inscribed 'Whoever does not yet understand it must pay for it! A small contribution to cleanness. Author: Josef Nikolaus Kleer. Price: on arrangement" and "Action artist"; on the ground in front of it, a copy of the last issue of the magazine Der Spiegel, with a caricature of the then British Prime Minister Margaret Thatcher on the cover, appearing as a holy knight on a dark-blue background in a reference to the Falklands War; in front of the red part, a copy of the "Red List," an official catalogue of remedies published by the German pharmaceutical industry; in front of the yellow part, a yellow housekeeping book with a second slip of paper carrying the inscription "Title: Housekeeping book. A work of art of the commune Tietzenweg, attic on the right. Not to be sold"; finally, lying somewhere on the ground, a red cheque-book. These items enabled the police to find the culprit quickly.'
'Kleer confessed that he was the assailant, and gave several reasons for his action, which can be summed up as follows: he had been afraid of the painting; Newman's work was a "perversion of the German flag" (which is horizontally divided into black, red and gold), it ought to "frighten the Germans" and did not belong to the Nationalgalerie; the purchase of such a work with public funds was irresponsible and artists earned too much money.'
Another report of the crime sates that 'The student's solicitor used Newman's statement acknowledging the hostility of his work to argue that the picture was an accessory to its own destruction' Furthermore, the report concludes saying that Kleer felt his actions completed the work, a view also held by Gerard Jan van Bladeren in regard to his own attack on Newman's Whos afraid of Red, Yellow and Blue III
 The Destruction of Art: Iconoclasm and Vandalism since the French Revolution
Gary Schwartz, Art in America. Issue: July, 1998
Review of Dario Gamboni's book
Peter Moritz Pickshaus, Hamburg, 1988
This quote taken from the website Art Vandals. An Excellent site created to accompany an exhibition by which Felix Gmelin recreates works which have been vandalised.