Iran's foreign minister delivered a blunt challenge to the United States on Saturday, saying Teheran is willing to help US troops withdraw from neighboring Iraq but only if Washington makes some tough policy changes. Foreign Minister Manouchehr Mottaki claimed US troops were responsible for at least half the violence tearing apart Iraq and that their departure would pay security dividends for the entire region. "If the United States changes its attitude the Islamic Republic of Iran is ready to help with the withdrawal from Iraq," Mottaki told the International Institute of Strategic Studies conference here. "Fifty percent of the problem of insecurity in Iraq is the presence of foreign troops." Mottaki echoed calls made last week by Iran's top national security official, Ali Larijani, for Gulf Arab countries to eject American bases in their countries and establish a regional security pact with Iran. Mottaki went further and offered deeper cooperation with the six Gulf Arab states on energy, tourism, business and counter-narcotics.