Diplomacy aimed to end the crisis in Ukraine may not succeed, German Chancellor Angela Merkel said Saturday, a day after returning from Moscow.

Merkel said the current crisis in the country “cannot be solved by military means” and “substantial steps” are needed jolt the violated September peace deal between Kiev and the pro-Russian separatists.

Addressing the Munich Security Conference, Merkel said of the latest peace efforts that "it is uncertain whether they will be successful." However she said that she and French President Francois Hollande, who accompanied her to Kiev on Thursday and Moscow on Friday, believe it is "in any case worth making this attempt."

"We have not yet had sufficiently good experiences" with agreements that have been made being honored on the grounds, she said, but that the answer to that can't be not to seek agreements.

Merkel also doubts the wisdom of supplying weapons to Ukraine, which some U.S. officials have advocated in the last week.

Merkel's speech was attended by Ukrainian President Petro Poroshenko and U.S. Vice President Joe Biden. She planned to hold a three-way meeting with both on the sidelines.

Russian Foreign Minister Sergey Lavrov and U.S. Secretary of State John Kerry are also attending the conference.  

Merkel, Hollande and Poroshenko plan to confer on Sunday by telephone with Russian President Vladimir Putin.  

Putin's spokesman, Dmitry Peskov, said after Friday's talks that efforts were moving forward.  

"Work is currently underway on drafting the text of a possible joint document on the implementation of the Minsk agreement, which would include the proposals made by the president of Ukraine and President Putin," Peskov said.

The Associated Press contributed to this report