The Russian economy was slowing even before President Trump’s latest threats. But the Kremlin has enough money to keep fighting in Ukraine.

"The key channel by which secondary tariffs on buyers of Russian energy could impact the global economy would be through the level of energy prices," says Kieran Tompkins from the consultancy Capital Economics. If the tariffs work, they will cut the flow of Russian oil and gas to global markets.

With a Friday deadline for Russia to agree to peace in Ukraine or have its oil customers face secondary tariffs, Trump has found a novel, but risky, use for his favorite trade tool.

The drop from Russia’s oil supply is not likely to be significant, with global prices set to remain stable in the near term, an analyst says.