Whether by accident or design, the United States and its partners in Europe have entered a sort of good-cop-bad-cop routine in their dealings with Russian President Vladimir Putin. As fighting escalates in eastern Ukraine, where Russia-backed rebels are trying to carve out an independent republic that would align with Russia, the annual Munich Security Conference on Saturday was dominated by world leaders taking very different positions on what to do about it.

Fresh from a meeting with Putin in Moscow on Friday, German Chancellor appeared to foreclose on the possibility of providing additional arms to the Ukrainian government, saying, "I understand the debate but I believe that more weapons will not lead to the progress Ukraine needs. I really doubt that.”

Related: Putin; U.S. Arming Ukraine Would Do ‘Colossal Damage’

Merkel, who grew up in the former East Germany and speaks Russian, may have the strongest relationship with Putin of any European leader. While she insisted that continued diplomatic efforts were the only option, she was notably pessimistic about their ultimate likelihood of success.

“It is uncertain whether it will lead to success but, from my point of view and that of the French president, it is definitely worth trying,” she said, referring to French President Francois Hollande, who accompanied her to Moscow on Friday.

For his part, Hollande said that he agreed with the continuation of diplomatic engagement. “Because if we are not able to reach, not a compromise, but a durable peace accord, we perfectly know the scenario: It has one name; it is called war.” What makes the current situation in Eastern Ukraine substantially different from a war already is far from clear.

While the United States’ European partners preached diplomacy and spoke against the introduction of additional weaponry, U.S. Vice President Joe Biden appeared at the conference with a much stronger message for Moscow.

Related: U.S. Edges Closer to a Dangerous Proxy War with Putin

“President Putin has to make a simple, stark choice,” he said. “Get out of Ukraine, or face continued isolation and growing economic costs at home.”

While he said that the U.S. remains in favor of a diplomatic solution, he added, “Too many times President Putin has promised peace and delivered tanks, and troops, and weapons.” Mr. Biden said. “We will continue to provide Ukraine security assistance. Not to encourage war but to allow Ukraine to defend themselves.”

Biden’s remarks reflect a hardening of the U.S. position toward Russia in recent weeks. The U.S. Congress has already voted in favor of sending arms to the Ukrainian government, while the Obama administration’s nominee for Secretary of Defense last week said that he would support such an action.

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Thousands of soldiers and civilians have been killed, and as many as a million people have been made refugees. Both sides are using heavy weaponry, including artillery and tanks. On the side of the separatists, virtually everyone except the Russia government says that the Kremlin is supplying not just materiel, but soldiers as well.

In Munich Saturday, Ukrainian President Petro Poroshenko made an emotional appeal for assistance from Europe and the U.S, which he highlighted by producing Russian passports and military ID cards that he said had been confiscated from Russian soldiers killed or captured in Ukraine.

"This is the best evidence for the presence and the aggression of Russian troops,” he said. “How much evidence does the world still need to recognize the obvious fact that that there is a foreign military [in Ukraine]?”

Merkel, Hollande, and Poroshenko were expected to speak with Putin on Sunday morning about moving toward a potential ceasefire.

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