BRUSSELS - Japan's trade minister sought an exemption from U.S. import tariffs on steel and aluminum on Saturday and called for "calm-headed behavior" in a dispute that threatens to spiral into a trade war.Minister Hiroshige Seko told a news conference his US counterpart Robert Lighthizer had only explained the schedule and procedure of the US actions in talks in Brussels. Seko said he believed there was still time for Japan to secure an exemption.US President Donald Trump signed an order on Thursday to set import tariffs of 25 percent on steel and 10 percent on aluminum, to come into effect in 15 days. But he exempted Canada and Mexico and held out the possibility of excluding other allies."We expressed our concern. It could disrupt the steel and aluminum markets of the world and have a negative impact," Seko told reporters after his meeting with US Trade Representative Lighthizer in which he sought an exemption for Japanese producers."We call for calm-headed behavior," Seko said.Japan, he said, would stick to World Trade Organization rules in terms of taking measures."If there is a violation, then we will seek consultations. We will look at the impact on Japanese businesses and make a final decision."