President also threatens tariffs on imports to US and repeats call for Nato countries to increase defence spending to 5%

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Donald Trump has made a combative return to the world stage, accusing oil producers of prolonging the Ukraine war by failing to cut prices, and threatening tariffs on all US imports.

In a typically blustering online address to the World Economic Forum in Davos, the new president called on Saudi Arabia and the oil-producers’ cartel Opec to cut the cost of oil, in order to choke off revenues to Russia and halt the conflict in Ukraine.