US President Barack Obama concluded his three-day visit to Africa recently, but as he did so the 12-year-old genocide in Darfur and other states in Sudan was still unfolding. Obama's strong position and active diplomacy to help end the crisis in South Sudan has been welcome, but it has been sad to see there has been no similar action to help end the crisis in Sudan. Sudanese President Omar Hassan Al-Bashir, a fugitive from the International Criminal Court (ICC), has been accelerating his genocidal campaigns in the Darfur, South Kordofan and Blue Nile states in Sudan, making them the killing fields of our time. Al-Bashir has been exploiting the divisions among the world powers, and these have failed to respond to his genocidal wars and gross violations of human rights across Sudan. The US, as a leading world power founded on the values and principles of justice, human rights and democracy, has a moral responsibility to act against genocide. In September 2004, Colin Powell, the then-US secretary of state, declared that the ongoing conflict in Darfur was “genocide.” This was a rare act in the history of the American response to genocide. By recognising the Darfur situation as genocide, the US put itself under a legal obligation to stop it, as enshrined in the Convention on the Prevention of Genocide of 1948, which has now become part of international law. The Obama administration is well informed about the ongoing genocide in Sudan. Before assuming office, Obama, Vice-President Joe Biden and US representative to the UN Samantha Power visited the region and met with Darfuri refugees in the early years of the Darfur genocide. Suzan Rice, the US national security advisor, was also outspoken about the genocide in Darfur. All of them pledged to stop it. Advocates, including myself, expected much more from Power, a champion of humanitarian intervention, an influential member of the US administration and the author of the compelling book A Problem from Hell: America and the Age of Genocide. In the book, Power poses a haunting question: “Why do American leaders who vow ‘never again' repeatedly fail to marshal the will and the might to stop genocide?” So why do policy-makers, including Power, repeat the same failure by not responding to this genocide of the 21st century? Obama is at the tail end of his presidency, and analysts also believe that US foreign interests have shifted from intervening in the affairs of African and Muslim countries towards repairing relations with old enemies like Iran and Cuba. The Iran nuclear deal is currently dominating the national debate in the US, especially with the looming elections. Public opinion is divided, mainly due to the sharp political differences between Obama and the Republican-dominated Congress. Al-Bashir is determined to exploit the current political climate in the US, but the Obama administration and the current Congress must not tacitly allow the suffering of countless human beings in Sudan to be their legacy. Earlier this month, a senior Sudanese diplomat in Khartoum announced that Sudan had invited Donald Booth, the US special envoy to Sudan and South Sudan, to visit Khartoum. According to the Sudanese diplomat, the sole item on the agenda of the visit is to discuss ways to normalise bilateral relations. Some observers have regarded this move as surprising given the problematic diplomatic relations between the two countries that have been in place since the Islamists seized power in Khartoum in 1989. Sudan has also blocked the US special envoy from visiting Sudan since 2013. Al-Bashir's regime complains that the US has repeatedly broken promises to normalise bilateral relations, despite Sudan's cooperation in allowing a smooth and peaceful referendum to take place in South Sudan and eventually recognising its results that led to the independence of South Sudan in 2011. It claims that the US has not rewarded it for its cooperation on counter-terrorism efforts. So why has Sudan now invited the US envoy to visit Khartoum? Some sources in Khartoum believe that the US recently took steps considered by Khartoum to be positive and encouraging. The first of these took place in February, when Ibrahim Ghandour, then a senior aide to Al-Bashir and now Sudan's foreign minister, visited Washington where he met with senior officials of the US administration. Ali Karti, the former Sudanese foreign minister, also visited Washington during that time, but the State Department distanced itself from his visit. Second, also in February, the US deputy assistant secretary of state for democracy, human rights and labour visited Khartoum and met with Sudanese officials. Third, the US Treasury's Office of Foreign Assets Control has relaxed its sanctions on Sudan to allow the export of personal communications equipment, including smartphones and laptops, as well the importation of some agricultural items. Fourth, the US has repeatedly recognised Sudan as a valuable partner in counter-terrorism efforts, seeing it as no longer harbouring or sponsoring terrorist organisations. Al-Bashir believes that the emergence of the Islamic State (IS) terrorist group will make him a more valuable asset to the US and may push the US to normalise relations with Sudan. Fifth, earlier this month the US Embassy in Khartoum condemned the Sudan People's Liberation Movement-North (SPLM/N) for its military activities in South Kordofan state. The move was widely reported and praised in the government media and was perceived by the regime as a positive sign that indicated a change in US policy. Sixth, also earlier this month, the US Embassy announced the resumption of immigration visa processing in Sudan for the first time in nearly 20 years. Dialogue is an important method of international and diplomatic relations. However, Al-Bashir is only interested in getting rid of US sanctions in order to consolidate his autocratic regime. He is not prepared to take any tangible measures to stop the ongoing genocide and gross violations of human rights that his regime has been perpetrating in Darfur and other states. How can a genocidal dictator remain in power and lead his people into a meaningful democratic transition when he himself has fractured Sudan? The UN Security Council has issued nearly 20 resolutions on Sudan under Chapter 7 of the UN Charter, but Al-Bashir has dishonoured them all. His real intention is to mislead the world, bide his time and continue his old bloody tactics. In March and April this year, Al-Bashir rejected calls for a national dialogue with his fellow citizens and, instead, imposed rigged single-candidate and single-party elections that were denounced by a majority of the Sudanese people and some key members of the international community. The ongoing genocide in Darfur, the Nuba Mountains and the Blue Nile, as well as the gross violations of human rights across Sudan, should shock the US and the world into action. Al-Bashir should not be allowed to exploit the current focus on the Iran nuclear deal and other world flashpoints. The US should send a clear message to Al-Bashir that it cannot and will not ignore the suffering of millions of innocent civilians who have been subjected to his genocidal campaigns. It is imperative that the US and its partners set a clear road map with specific benchmarks that apply punitive measures, including targeted sanctions, to stop the genocide, realise an inclusive peace and facilitate a political transition in Sudan. It should be clear to Al-Bashir that there can be no normalisation as long as the ongoing genocide and tyranny continues. Obama can still fulfill his long-overdue promise to stop this genocide of the 21st century. Since his administration considers the prevention of genocide and other mass atrocities to be a core American national security interest he should not be held back by narrowly defined national interests. If there is the will to do so, stopping the horror in Sudan can still be part of Obama's foreign policy legacy. It is not too late for Obama to fix his Sudan policy. The writer is a visiting fellow at Cornell University's Institute for African Development in the US and a research fellow at the Department of Public Policy and Administration at the American University in Cairo.