Foreign ministers from the 57-member OSCE met in Vienna on Thursday with US Secretary of State Rex Tillerson and Russia's Sergei Lavrov set to discuss a possible UN peacekeeping force for Ukraine.
As dignitaries from Europe, North America and Asia gathered in Vienna's magnificent Hofburg palace, the regional group's leader admitted the sides remained far apart.
"We've reached an absolute low point regarding confidence between the main players," the Organization for Security and Co-operation in Europe's secretary general Thomas Greminger told reporters.
After long resisting the idea, Russia has suggested deploying a UN peacekeeping force to help end the war between Ukraine's government and Russian-backed separatists in the east of the country that has killed over 10,000 people since 2014.
But Western powers, led by the United States, want a force with a robust mandate that would allow it to protect the 600 OSCE monitors there, police ceasefire lines and investigate ceasefire breaches across eastern Ukraine.
They fear that a United Nations mission that only polices the front line would serve to create a frozen conflict that would de facto lock in Russian gains from its intervention in Ukraine.
Before arriving in Vienna, Tillerson, who was due to meet Lavrov later on Thursday on the sidelines of the OSCE meeting, said agreeing on an effective force was now Washington's main priority.
"We prioritise ending the violence, that's our first priority, and to seek to do that we need to put a peacekeeping force in place," Tillerson said.
"Russia has long resisted a peacekeeping force, but they have agreed now," he said after NATO talks on Wednesday.
"I think it's significant that we're talking about the right thing," he said.
But he warned that there was a "significant difference" over the mandate the force will have "and that's why we continue to talk with the Russians."
- Diplomatic standstill -
The UN peacekeeping force was not on the official agenda for the two-day OSCE gathering in Vienna, which involved some 40 foreign ministers, but was expected to be a big topic on the sidelines.
The OSCE was created during the Cold War to ease dialogue between East and West.
But after the collapse of the Soviet Union 25 years ago it expanded and now has 57 members including the United States, Russia and Ukraine.
The Vienna-based body monitors conflicts, elections, media freedom and human rights. Italy will take over the rotating presidency from Austria in January.
The nosedive in relations between Russia and the West over Ukraine and other points of contention has brought OSCE decision-making to a near-standstill, diplomats say.
In the past the annual meeting of OSCE foreign ministers produced a joint communique but this hasn't been possible for several years.
Earlier this year the OSCE was without a secretary general for several weeks after member states were unable to agree on a candidate.
Other key posts were left vacant for even longer and there have been major delays agreeing budget questions.
"Everything is blocked," a Western diplomatic source told AFP on the eve of the two-day meeting in Vienna on Thursday and Friday.