On 23 May , a day after Saleh refused Agree_or_refuse_to_act to sign Sign_agreement the transition agreement , Sheikh Sadiq al-Ahmar , the head of the Hashid tribal federation , one of the most powerful tribes in the country , declared Expressing_publicly support Supporting for the opposition and his armed Bearing_arms supporters came into conflict Hostile_encounter with loyalist security forces in the capital Sanaʽa .