Negotiations broke up after more than five hours on Wednesday with the pro-Russian rebels reporting little to no progress.
US Secretary of State John Kerry rules out committing "boots on the ground" at a meeting of 10 nations on the sidelines of the recent Nato summit.
Nato leaders have agreed to boost the military alliance's readiness to meet fresh security threats by setting up a new rapid reaction force.
The Western alliance at last has an enemy that seems to fit its bill - Nato is ready to defend Europe from 'Russian aggression'.
A Taliban attack has killed 18 people and wounded around 150 in Afghanistan, while Nato has warned that accords over Afghan troops have to be signed.
Russian Foreign Minister Sergei Lavrov has warned Nato and the US not to offer Ukraine membership of the alliance, ahead of a Nato summit.
The Ukraine crisis is the most serious threat to Euro-Atlantic security since the Cold War, according to Nato head Anders Fogh Rasmussen.
A suicide attack has claimed six lives and air attacks have killed 10 children over a weekend that served as a reminder of Afghanistan's conflict.
Syrian President Bashar al-Assad will deliver a rare speech on Sunday about the uprising against his rule, which has killed 60000 people.
Officials say Serbia's ambassador to Nato committed suicide by leaping from a busy parking garage platform at Brussels airport.
Nato has told President Bashar al-Assad that any use of chemical weapons in his fight against rebel forces would be met by an international response.
US President Barack Obama has delayed General John Allen's nomination as Nato's supreme commander pending a probe into a sex scandal.
A suicide bomber detonated explosives near the heavily barricaded Nato headquarters in Kabul on Saturday, Nato and local officials said.
Three US Marines have been shot dead by an Afghan worker on a military base in southern Afghanistan, in a deadly 24 hours for Nato-led forces.
The threat from Somali pirates is receding but the international community must continue to work together to eliminate the menace
Nato states have expressed mounting anger over the downing of a Turkish fighter jet by Syria as they readied for an emergency meeting on the shooting.
At least four French soldiers were killed and several wounded in a suicide attack against a convoy of Nato-led troops in eastern Afghanistan.
Seven months on from Muammar Gaddafi's butchering in the ruins of Sirte, the fruits of liberal intervention in Libya are now cruelly clear.