US President Donald Trump on Sunday defended a recent decision to waive sanctions on Russian diesel, as relations between Washington and Ukraine soured further.Mr Trump on Friday waived key provisions of a recent package of sanctions against Russia, saying in an executive order that “such a waiver is in the national interests” of the US. The order waived a requirement by him to raise duties on Russian goods imported into the US by up to 500 per cent, and a separate requirement to place tariffs of up to 100 per cent on China, India and other top buyers of Russian…