MILAN (Reuters) -The European Union has already prepared a list of tariffs worth 21 billion euros ($24.52 billion) on U.S. goods if the two sides fail to reach a trade deal, Italy's Foreign Minister Antonio Tajani said in a newspaper interview on Monday. President Donald Trump on Saturday threatened to impose a 30% tariff on imports from Mexico and the EU starting on Aug. 1, after weeks of negotiations with major U.S. trading partners failed to reach a comprehensive deal. Tajani also told daily Il Messaggero that to help the euro zone economy the European Central Bank should consider a new "quantitative easing" bond-buying-programme, and more interest rate cuts.