US and Russian officials are meeting in Geneva on Monday for critical talks on rising tensions over Ukraine.
Worries have been mounting in the United States and Europe over Russia's military build-up close to its border with Ukraine.
Russia is pushing for a deal to make sure Ukraine is not allowed to join the NATO military alliance. A top Russian diplomat predicted “difficult” talks after attending a working dinner with US officials in Geneva on Sunday night.
However, the US says it will make “no firm commitment” during the talks, and that only security issues will be discussed.
A State Department spokesman said Washington's top official at Sunday's dinner "stressed the United States’ commitment to the international principles of sovereignty, territorial integrity, and the freedom of sovereign nations to choose their own alliances," a reference to Ukraine and its aspirations of joining NATO.
A Russian independent political analyst, Dmitry Oreshkin, says President Putin cannot accept Ukraine or Georgia joining NATO.
"He might have come to terms with the Baltic states being a lost cause, a part of NATO and so on, but he has decided to hold on to the end in Ukraine.”
“And the only way to secure his strong-arm political authority over Ukraine is creating tension at the border," he added.
Troops remain on high alert
Meanwhile, in eastern Ukraine, troops remain on high alert, amid fears of a Russian invasion.
Last week the European Union's top diplomat, Josep Borrell, visited the Donbas region.
It was the first trip of an EU foreign policy chief there since the conflict erupted in 2014.
Washington and Moscow have excluded Brussels from the diplomatic talks aimed at de-escalating the situation at the Ukrainian-Russian border.
Borrell did not hide his exasperation last Wednesday during his visit to the region.
"On this dialogue, there are not two actors alone. It's not just US and Russia. If you want to talk about security in Europe, Europeans have to be part of the table," he said.
This sentiment has been echoed by the EU’s ambassador to the UK, João Vale de Almeida, who issued a warning to Russia.
"The European Union and member states have a very common position of strength,” he said.
“The United States is together, the NATO allies are together and we are saying very clearly - and these are very clear words - that there will be massive consequences and severe costs if Russia adventures into Ukraine with military action."
U.S. Secretary of State Antony Blinken tried to appease worries telling ABC's "This Week" on Sunday: "We've been very clear with Russia -- repeatedly -- that we are not going to do or commit to anything about Europe without Europe. So, anything that goes to Europe's security interests will be done in full coordination with them, with Europeans at the table."
However, the EU isn't the only party being left out of the talks taking place in Geneva, Ukraine has also not been invited.
While the US has made it clear it will not intervene militarily if Russia invades, Ukrainians have been eager to demonstrate in Kyiv that they will stand together and resist any kind of attack.