Complex sentence: In 1991, Japan pledged billions of U.S. dollars for the Gulf War, but constitutional arguments prevented a participation in actual war, leading Iran to criticise Japan for just pledging money and did not appreciate the way Japan co-operated in the Gulf War.
Split into simpler sentences: In 1991, Japan pledged billions of U.S. dollars for the Gulf War, but constitutional arguments prevented a participation in actual war. Iran criticised Japan for just pledging money and did not appreciate the way Japan co-operated in the Gulf War.