PRESIDENT OBAMA’S tour of Africa this week has been defined as much by the countries he is skipping as those he is visiting. Among those excluded from the itinerary are Kenya, the homeland of Mr. Obama’s father, where the newly elected president and vice president are under indictment by the International Criminal Court; and Nigeria, the continent’s most populous country, which recently was accused by the State Department of “gross human rights violations” in its campaign against Islamic extremists.

Mr. Obama instead is visiting South Africa, whose iconic leader Nelson Mandela appears near death; and two small, untroubled nations, Senegal and Tanzania. That’s in keeping with the themes of the trip outlined by the White House: the promotion of U.S. trade and investment in a continent where economic growth is picking up and support for democratic institutions. Mr. Obama also wants to encourage a new generation of African leaders, though he may find himself eulogizing, in Mr. Mandela, one of the greats of the past.

As African leaders frequently note, the president’s outreach is overdue. It has been four years since his previous, 20-hour visit to Africa as president, a stretch during which he has made multiple visits to Asia and Latin America. During that time China has made a major push to extend its influence in Africa and, in some important ways, has succeeded: At $200 billion, its annual trade with the continent is twice that of the United States. During regular visits by its presidents, including one by new leader Xi Jinping in March, Beijing has been showering governments with billions in aid, with no apparent political strings.

Mr. Obama can’t match that largesse, but he could, directly or otherwise, draw distinctions between the forms of engagement offered by China and the United States. The president will hold an interactive town hall meeting in South Africa, something Mr. Xi would never hazard. Mr. Obama’s support for democracy offers an opportunity for contrast with China’s unqualified backing for strongmen like Robert Mugabe in Zimbabwe and Omar Hassan al-Bashir in Sudan.

What the president should not do is use his tame schedule to dodge the continent’s toughest problems. These include not only lingering dictatorships but the rise of Islamic terrorist groups in northern Africa and continuing conflicts in Sudan and the Congo, which Mr. Xi visited. In an interview earlier this year, Mr. Obama wondered why the United States should consider intervention in Syria, rather than Congo. Since then, his administration successfully co-sponsored a U.N. Security Council resolution that mandated the dispatch of a 3,000-strong U.N. “intervention brigade,” including troops from South Africa and Tanzania, to carry out offensive operations against Congolese rebels. That was the right call. Perhaps Mr. Obama can now explain why he believes such outside intervention is merited in Congo, but not in Syria.