CAIRO - The leaders of Ethiopia and Egypt vowed on Sunday to iron out their differences over a dam Addis Ababa is building on the Nile River that Cairo fears threatens its water supplies.Talks over the Grand Renaissance Dam, Ethiopia's $4 billion hydroelectric project, have been deadlocked for months. But at a press conferee in Cairo, Ethiopian Prime Minister Abiy Ahmed and Egyptian President Abdel Fattah al-Sisi signaled they had made a breakthrough."We have come a long way in building confidence and strengthening bilateral cooperation," Sisi said.Ahmed, speaking in his native Amharic language, said Ethiopia was committed to ensuring Egypt's share of Nile water."We will take care of the Nile and we will preserve your share and we will work to increase this quota and President Sisi and I will work on this," Ahmed said, addressing Egyptians.Safeguarding Egypt's share of the Nile, its main source of drinking water and water for industry and farming, is at the top of Sisi's agenda as he begins his second term in office.The two sides agreed to take steps to put into effect an agreement - which also includes Sudan - to set up a fund for investing in infrastructure in the three countries.Towards the end of their news conference, Sisi asked Ahmed to swear to God before the Egyptian people that he will not hurt Egypt's share of the Nile."I swear to God, we will never harm you," Ahmed repeated the words in Arabic after Sisi, who thanked him for releasing jailed Ethiopians.