"The United States is all in on Africa," Biden told Angolan President Joao Lourenco, who called Biden's visit a key turning point in U.S.-Angola relations dating back to the Cold War.

But even as the visit was meant to counter China's influence on the African continent of over 1.4 billion people by showcasing a U.S. commitment of $3 billion for the Lobito Corridor railway redevelopment linking Zambia, Congo and Angola, China announced its own move.

The corridor is meant to make it easier to move raw materials for export and advance the U.S. presence in a region rich in critical minerals used in batteries for electric vehicles, electronic devices and clean energy technologies.

China already has heavy investments in mining and processing African minerals, and on Tuesday it announced it is banning exports to the United States of gallium, germanium, antimony and other high-tech materials. The announcement came a day after the U.S. expanded its list of Chinese technology companies subject to controls.

The U.S. for years has built relations in Africa through trade, security and humanitarian aid. The 800-mile (1,300-kilometer) railway upgrade is different, with shades of China's Belt and Road infrastructure strategy in Africa and other parts of the world.

Biden will visit the Angolan coastal city of Lobito on Wednesday for a look at the corridor's Atlantic Ocean outlet. The project also has drawn financing from the European Union, the Group of Seven leading industrialized nations, a Western-led private consortium and African banks.

White House national security spokesperson John Kirby said the corridor's completion is "going to take years but there's already been a lot of work put in."

That means much of it may fall to Biden's successor, Republican Donald Trump, who takes office on Jan. 20.

Asked whether the project could proceed without support from Trump, Kirby said it was the Biden administration's hope "that they see the value too, that they see how it will help drive a more secure, more prosperous, more economically stable continent."

Kirby, speaking aboard Air Force One as Biden flew to Angola, said the corridor was about more than simply trying to outpace Beijing geopolitically.

"We're not asking countries to choose between us and Russia and China. We're simply looking for reliable, sustainable, verifiable investment opportunities that the people of Angola and the people of the continent can rely on," he said.

"We don't think because we're bigger and more powerful that we have all the answers," Biden said Tuesday, pledging to use the trip to listen.

Angola's president said he'd like to see a public-private partnership to increase energy production.

Biden had promised to visit Africa last year, after reviving the U.S.-Africa Summit in December 2022. But the trip was delayed until this year and then pushed back again this October because of Hurricane Milton -- reinforcing a sentiment among Africans that their continent is still a low priority for Washington.

The last U.S. president to visit sub-Saharan Africa was Barack Obama in 2015. Biden attended a United Nations climate summit in Egypt in North Africa in 2022.

In Angola, Biden will meet with leaders of African business engagement groups he helped found and then visit Angola's National Slavery Museum. The site was once the headquarters of the Capela da Casa Grande, a 17th century temple where slaves were baptized before boarding the ships that took them to America.

Kirby said Biden will give a speech there acknowledging "both the horrific history of slavery that has connected our two nations, but also looks forward to a future predicated on a shared vision that benefits both our people."

After arriving in Angola's capital, Luanda, on Monday evening, Biden met briefly with Wanda Tucker, a descendant of William Tucker, the first enslaved child born in the United States, the White House said.

William Tucker's parents were brought to colonial Virginia from Angola in August 1619 aboard the Portuguese ship the White Lion.