After President Donald Trump threatened Iran via tweet Sunday, climate campaigners on Monday drew renewed attention to the danger of pursuing war for oil.

Their calls came after Trump tweeted the U.S. is "locked and loaded" in response to a weekend attack on Saudi oil facilities and suggested he was merely waiting for the directive from Riyadh. The White House has blamed Iran, without evidence, for the attacks.

The focus on wars for oil came as thousands of young activists worldwide mobilize for the global #ClimateStrike on Sept. 20.

Commenting on the simmering tensions, author and 350.org co-founder Bill McKibben wrote on Twitter, "Getting ready for war to insure the supply of a substance that is wrecking the planet."

Climate group Greenpeace International weighed in as well, urging the use of "diplomacy over force" and "peaceful renewable energies" over fossil fuels.

Between 1/4 and 1/2 of all wars between countries since 1973 are linked to oil. Oil has fuelled violence and the climate emergency for far too long. We must choose diplomacy over force, and peaceful renewable energies, like wind and solar, over dirty, destructive oil. https://t.co/dUdkvum0mW — Greenpeace PressDesk (@greenpeacepress) September 16, 2019

"Fossil fuels are dangerous," tweeted environmental scientist Jonathan Foley late Sunday. "For our security. For our economy. For our health. And for the planet."

"Let's not be held hostage by this industry any more," he added. "It's time to move to a better world."