A permanent ceasefire in east Ukraine must be observed unconditionally, negotiators representing Russia and Ukraine agreed on Wednesday, according to CNN.

The two countries, along with Germany and France, held talks on Wednesday at the Elysee Palace in Paris. Since 2014, the four countries have held talks under the Normandy Format with the aim to secure peace in eastern Ukraine.

Tensions between Russia and Ukraine intensified after the former country, last year, gathered 1 lakh troops near the Ukrainian border.

Russia’s chief negotiator Dmitry Kozak said on Wednesday said that the ceasefire must be observed unconditionally, but added that many other matters remain unresolved. He added that the obligation to enforce agreements to ensure peace rests with Ukraine’s armed forces and the armed formations of the Donetsk People’s Republic and Luhansk People’s Republic [self-proclaimed states officially within Ukraine],” according to CNN.

Ukraine’s negotiator Andriy Yermak said that the country was prepared to negotiate round the clock to de-escalate tensions.

Both the negotiators said that the talks will resume in Berlin after about two weeks.

Meanwhile, the United States and the North Atlantic Treaty Organization told Russia in separate communications on Wednesday that they will not offer any concessions on Moscow’s main demands, AP reported.

They said that there will be no change to NATO’s open-door membership policy, and turned down Russia’s demand that Ukraine be permanently banned from joining the alliance. Both the US and NATO also said that deployment of troops and military equipment in eastern Europe are not negotiable.

United States Secretary of State Antony Blinken said that any invasion by Russia will be met with massive consequences.

The official added that the United States has handed over a document to Russia suggesting a diplomatic path forward to resolve the crisis, according to AP.

“...There’s no doubt in my mind that if Russia were to approach this seriously and in a spirit of reciprocity with a determination to enhance collective security for all of us, there are very positive things in this in this document that could be pursued,” Blinken said. “We can’t make that decision for [Russian President Vladimir] Putin.”

On Tuesday, United States President Joe Biden said that his government may consider sanctions personally on Putin in the event of a Russian invasion of Ukraine, according to Reuters. In response, Kremlin spokesperson Dmitry Peskov said that such a move would be “politically destructive”.

Peskov had earlier reportedly said that imposing personal sanctions on Putin would amount to cutting off diplomatic ties.