TUNIS/SEOUL: Germany’s foreign minister warned Friday time is running out to end the “madness” in Ukraine, where tensions are soaring in what Kiev says is a Russian bid to trigger a “third world war.”

Frank-Walter Steinmeier was on a trip to Tunisia with his French counterpart Laurent Fabius, and both called for a “de-escalation” of a crisis that has seen Ukraine’s army launch a major offensive to dislodge pro-Moscow gunmen.

“There is not much time to end this madness,” Steinmeier warned at a news conference in Tunis, shortly after Ukraine’s interim prime minister accused Russia of seeking to trigger a “third world war.”

“All sides must come back to their senses,” he said, pointing to those “in conflict within Ukraine and those who support them from outside.”

Kiev and Washington accuse Moscow of backing the pro-Russian insurgents, a charge the Kremlin flatly denies.

Fabius, meanwhile, said Paris and Berlin were making a joint call for a “de-escalation” of the crisis.

The tense situation has triggered an increasingly strident war of words between Russia and the United States, amid concerns it could evolve into outright war.

Meanwhile, the US and Europe are laying the groundwork to sanction broad sections of Russia’s economy if Moscow invades eastern Ukraine, President Barack Obama said Friday, even as he acknowledged those sanctions may fail to deter Vladimir Putin.

So far, the US has slapped sanctions on individuals but hasn’t targeted entire economic sectors, such as Russia’s critical energy sector. Obama’s comments affirmed that barring a full-on military incursion, Russia is unlikely to face those beefed-up sanctions, which could ricochet and harm US allies in Europe that do business with Russia.

“We’ll continue to keep some arrows in our quiver in the event we see further deterioration,” Obama said during a news conference in South Korea, where the president was traveling.

Obama said he planned to call key European leaders on Friday evening to discuss what’s transpired since a deal was reached in Geneva last week to de-escalate the crisis. Echoing harsh comments from US Secretary of State John Kerry, Obama said Russia has failed to uphold the deal by urging pro-Russian militias to give up buildings they’ve occupied in Ukrainian cities.

Seeking to convey strong unity among the US and European nations, Obama said he was “deeply encouraged” by the consistent condemnation of Russia’s actions in Crimea that have emanated from capitals in Europe, North America and across the globe.