(Adds arrival in Qatar, quotes by Foreign Ministry on Bahrain) By Ahmed Hagagy KUWAIT, JULY 26 (Reuters) - Iran's foreign minister called on Sunday for a united front among Middle Eastern nations to fight militancy, in his first regional trip since Iran reached an agreement With world powers on the country's nuclear programme - an agreement that raised fears among its Gulf Arab neighbours. "Any threat to one country is a threat to all ... ** country can solve regional problems without the help of others," Mohammad Javad Zarif said at a news conference hosted by the Iranian embassy in Kuwait. Zarif earlier met Emir Sheikh Sabah al-Ahmed al-Sabah and Kuwait's foreign minister, Sheikh Sabah al-Khaled al-Sabah, who was **t present at the news conference.