The US President's threat has been further sanctions against Russia and tariffs on goods from all countries that trade with Russia. This could, among other things, affect countries that buy Russian oil.
But the picture is complicated by the message from the Russian power headquarters Kremlin on Thursday about a summit with Trump and his Russian counterpart Putin "in the coming days".
Tor Bukkvoll, the head researcher at the Norwegian FFI (Defence Research Institute), wonders how much Trump's threat affects Putin.
I do not think it will have any major impact, he says.
He gets support from Julie Wilhelmsen, researcher at Nupi (Norwegian Foreign Policy Institute.
It is still ruled out that the Kremlin agrees to Trump's ultimatum by saying yes to a complete ceasefire, she says.
