Relations between the two countries since the 1989 Sudanese coup have had their ups and downs. They reached a nadir in 1995, when elements of the Sudanese government were complicit in a plot by an Egyptian terrorist group, Gama'a Islamiyya, to assassinate Egypt’s president, Husni Mubarak, while he was en route from the Addis Ababa airport to an Organization of African Unity (now African Union) summit in Ethiopia’s capital. By the end of 1999, Egyptian anger toward Sudan had subsided, and President al-Bashir visited Egypt, where the two leaders agreed to normalize diplomatic relations. Al-Bashir returned to Cairo in 2002, at which time they expanded cooperation on a variety of practical issues. Mubarak repaid the visit by going to Khartoum the following year. In 2004 al-Bashir again went to Cairo, where the two leaders signed the Four Freedoms Agreement dealing with freedom of ownership, movement, residence, and work between the two countries. There has been cooperation on counterterrorism and development projects drawing water from the Nile, and the two governments agreed to establish a free-trade zone along the Sudan–Egypt border, where they would exchange commodities free of duty. Sudan has particularly appreciated Egyptian verbal and moral support for its policy in Darfur. Egypt also sent troops to the United Nations–African Union Mission in Darfur. Egyptian investments in Sudan reached US$2.5 billion by 2008 while Sudanese investments in Egypt totaled almost US$200 million. By 2010 Egyptian–Sudanese relations were better than they had been in many years, although several long-term contentious issues, such as the future status of South Sudan, ownership of the Hala’ib Triangle, and use of Nile water, remained unresolved.