A bitter trade battle between the United States and its commercial rivals intensified on Wednesday as controversial US tariffs on imported steel came into effect. Within hours, Japan became the latest country to file a complaint against the tariffs at the World Trade Organisation (WTO) in Geneva. EU Trade Commissioner Pascal Lamy said late on Tuesday that it would be "a question of days" before the EU issued quotas on steel imports to prevent its own industry being damaged by steel redirected from US markets. The US has unilaterally imposed tariffs of up to 30% on imported steel for three years, claiming that other countries are "dumping" steel at below the cost of production and damaging its domestic industry.