Across Africa, the approaching presidency of Donald Trump has provoked deep uncertainty over how the United States will pursue policies ranging from counter-terrorism and trade, to aid and climate change.

Many African countries had high hopes that Barack Obama would bring transformative benefits to the continent and were left disappointed as he winds down his time in office.

But Trump's rise to power poses fresh questions that reveal the lack of concrete detail on his foreign policy plans -- while the president-elect himself has seldom addressed African issues directly.

One possible pointer is Trump's often repeated vow to kill "terrorists", which may lead to more aggressive US intervention against Islamist forces such as Nigeria's Boko Haram, linked to the Islamic State group, and Shabaab militants in Kenya, Somalia and elsewhere.

"Donald Trump can be described as a strongman leader, and strongman leaders tend to only see military solutions," Ryan Cummings, director of the intelligence firm Signal Risk in Cape Town, told AFP.

"The US directly deploying in Africa or having a more overt presence would be a salient recruitment tool for many armed groups.

"The question is whether he is going to assist on the democratisation reforms and other projects that help stop extremism?"

Any increased US intervention would, however, go against Trump's isolationist stance -- a paradox that highlights increased unpredictability under his watch.

One of Trump's clearest themes on the campaign trail was his opposition to international trade deals that he says have put millions of Americans out of work.

That could spell trouble for the African Growth and Opportunity Act (AGOA), which gives 39 African nations duty-free access to the US market on about 7,000 products including textiles, cars, fruit and wine.

- Less aid money? -

Obama used AGOA as a tool to promote human rights, cutting Swaziland out of the deal in 2015 over alleged oppression in the small southern African nation.

In contrast, Trump's victory acceptance speech on Wednesday suggested a more protectionist approach to international relations, stressing "we will always put America's interests first".

Trump's potential pivot to isolationism could also impact the aid money that the US spends on health, education, agriculture and humanitarian crises across Africa.

USAID spent $700 million in Malawi alone over the last five years on a programme to improve quality of life in one of the world's poorest countries.

"Isolationism is implicit in all of his 'make America great again' rhetoric," said Zachary Donnenfeld, researcher at the Pretoria-based Institute of Security Studies.

"There is also evidence to suggest that he may have support for rolling back America's commitments to improving human development abroad."

Africa is seen as especially vulnerable to drought and floods caused by climate change, and Trump's election has shaken the global effort to reduce greenhouse gas emissions.

He has dismissed alarm about global warming and threatened to renegotiate or cancel US backing for the landmark Paris climate deal signed last year.

As African leaders rushed to congratulate the incoming president, Peter Vale, a professor of humanities at the University of Johannesburg, advised them to try to build whatever relationship they can with the Trump government.

"Africa is likely to slide down the list of foreign policy priorities of a Donald Trump administration," Vale wrote in an analysis briefing.

"He is going to be intolerant and disinterested in issues around the domestic politics of African countries.

"The worst that African countries can do, however difficult it will be politically, would be to show their displeasure and hold their noses."