U.S. Secretary of State John Kerry has arrived in the Democratic Republic of Congo, where he will meet with President Joseph Kabila.

The two leaders are expected to discuss recent security gains against rebel groups in eastern Congo.

Kerry commented on Ukraine's unrest shortly after arriving in the D.R.C. capital, Kinshasa, on Saturday. He welcomed the release of international monitors who had been held by pro-Russian separatists in eastern Ukraine for more than a week.

US African policy

Earlier Saturday, Kerry said the Obama administration is committed to helping African leaders resolve conflicts that threaten economic growth and social development. In a speech in Addis Ababa, Secretary Kerry outlined U.S. policy toward Africa.

In too much of Africa, Secretary Kerry says the threat of violence or all-out war "prevent even the first shoots of prosperity from emerging." But he says Africans today have an opportunity to "bend the arc of history towards reform, not retribution; towards peace and prosperity, not revenge and resentment."

Backing African Union efforts, Kerry says the Obama administration will continue to support fighting al-Shabab in Somalia, tracking down the Lord's Resistance Army, and strengthening Nigeria's fight against Boko Haram's campaign of terror and violence.

"Let me be clear," he said. "The kidnapping of hundreds of children by Boko Haram is an unconscionable crime, and we will do everything possible to support the Nigerian government to return these young women to their homes.

In a speech to African diplomats at a botanical garden outside Addis Ababa, Kerry said Washington will continue to back French and African forces in the Central African Republic as well as regional efforts to resolve the root causes of conflict in the Great Lakes.

Following his visit to South Sudan Friday, Kerry pressed President Salva Kiir and rebel leader Riek Machar to come to talks in the Ethiopian capital on forming a transitional government.

"If both sides do not take bold steps to end the violence, they risk plunging South Sudan into greater desperation and even famine. And that famine could be right around the corner if we don't turn the corner ourselves in the next days," he said. "They will completely destroy what they claim they are fighting for if we do not make a difference now."

He says the United States is working closely with African leaders to tackle corruption and illicit financial transactions because transparency and accountability attract greater investment and create a more competitive marketplace.

Kerry says the Obama administration is helping combat climate change with $1 billion in private-sector financing for an African clean energy initiative.

"Climate change is a global challenge and it's going to threaten this continent and all continents in profound ways if it is not matched by global cooperative action," he said.

From Ethiopia, Kerry traveled to the Democratic Republic of Congo for meetings with President Joseph* Kabila before wrapping-up this Africa trip in Angola in talks with President Jose Eduardo dos Santos.