The US and NATO need to write down their security guarantees vis-a-vis Russia "because Russia will not be waiting indefinitely," Russian Foreign Minister Sergei Lavrov says after multiple rounds of talks that seemed to bring the sides no closer.
NATO members have been on edge for weeks because of Russian troop build-ups near Ukraine's border, which have sparked worries that Russia might attempt to encroach on Ukrainian territory, as it already did in 2014.
Russia denies it has any such intentions and has, in return, argued that its security is not guaranteed so long as the NATO military alliance commits to no further eastward expansion, specifically in Ukraine.
German Defence Minister Christine Lambrecht warned Russia of the consequences of any attack on Ukraine on Friday.
"Russia has no veto when it comes to (NATO) alliance issues and cannot blackmail us," she said in parliament in Berlin.
There was still room for negotiations, she said.
"We must exhaust all options to resolve this conflict."
"The security of our allies is our security, both in central and eastern Europe... the Russian deployment on the Ukrainian border goes against all rules of peaceful coexistence," she said.
Russian and US representatives engaged both in direct talks this week, as well as in talks organised by NATO and the Organisation for Security and Co-operation in Europe (OSCE).
But neither side reported much progress.
According to a report by Russia's TASS news agency, Lavrov said the US and NATO are working to water down security guarantees.
"As for the plans for reducing this process to nothing, they certainly exist. Everybody understands that the prospects for achieving accord depend on the United States.
"Whatever some may say about the need for consultations with the allies and for involving all OSCE members, it's nothing but a lame excuse and an attempt to procrastinate," Lavrov said.
"We wish to see a position stated on paper. We wish to have answers article by article, item by item, in both documents: this is suitable and this is not suitable, and, if something is not suitable, why."
At a meeting in the north-western French port city of Brest, the foreign ministers of the European Union agreed on a 10-point plan for a unified approach to Russia.
In view of the Russian troop build-up near Ukraine, the plan envisages a united approach based on a mixture of deterrence and dialogue.
For example, preparations for new sanctions are to be continued with partners such as the US.
At the same time, the readiness for confidence-building measures and the support for possible new agreements on disarmament and arms control are stressed.
As the row continued, there was a cyberattack that paralysed Ukrainian government websites.
Officials in Kiev said the attack originated in Russia, citing "initial data".
Australian Associated Press