The United States lashed out on Thursday at "predatory" Chinese and Russian policy in Africa and unveiled a new strategy for using economic muscle to counter its rivals' grips on the continent.An increasingly assertive Beijing and Moscow "pose a significant threat to US national security interests" in resource-rich Africa, White House national security advisor John Bolton said in a speech he was to deliver later.Their "predatory practices" stunt economic growth and independence, while hampering US trade and military goals, he said in the text of the speech previewed by AFP.China in particular has made dramatic inroads in Africa with direct investment, aid and infrastructure projects that leave partners burdened by heavy debt - and under long-term Chinese influence.At a time when the Pentagon wants to reduce its Africa footprint, the United States says its best weapon in the power struggle will be to build partnerships through trade.African governments will from now on find a tighter-fisted approach to traditional aid, Bolton said, with an end to "indiscriminate assistance across the entire continent."A senior Trump administration official said there is longtime US "frustration" with corrupt African aid recipients.Trump's business instinctsHe said Bolton would call out South Sudan in particular as having fallen from favor.Washington "does not intend to go forward with spending hard-earned United States tax payer dollars to subsidize some of the kleptocratic regimes and violators of human rights," the US official said, on condition of anonymity, ahead of the speech.But where the Trump administration does want to see money flowing is through the private sector.That would not only suit Trump's business instincts, but accentuate US strengths over its great power rivals, the official said."We're going to try to connect harder than we've ever done before -- in a very focused effort -- US businesses and African markets and vice versa," the official said."We're going to encourage African leaders to choose high-quality, transparent, inclusive investment from the US (contrasting) to that of China and Russia.""The USA brand is still very strong," the administration official said.Military 'scale back' Bolton will use his speech to tell African leaders that "in our economic dealings, we ask only for reciprocity, never for subservience."China, by contrast, deliberately leads client states into debt, "promoting corruption," the US official said, while "Russia is using corrupt practices to gain influence and leverage with a number of African countries."The official said that Chinese control of Djibouti's Doraleh port and growing influence over Zambia, as well as Russia's deepening presence in the Central African Republic, were among the top concerns.There's also worry about the role of Russia in war-torn Libya, where Washington is likewise reviewing its strategy, the senior official said.The competition with China and Russia comes as Washington prepares to dial down its already modest military response to the spread of Islamist militant groups in Africa.Instead, Washington wants regional players to take more responsibility for their own security, with a view to boosting Washington's use of softer power.The Pentagon "probably will scale back over time. It won't be abrupt, but they will be able to scale down," the Trump administration official said."It may be that as the (defense department) scales back, we figure out where State Department can scale up and how we can again enhance the capacity."* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.