U.S. and Russian officials have kicked off a series of high-stakes talks in Geneva on Monday as tensions remain higher than ever over Ukraine.

Russia has been building up its military presence at its border with Ukraine in recent months, leading to concerns that Russia President Vladimir Putin is planning on invading the country. Russia has denied such claims, saying it has a right to place troops where it likes within its own territory.

Putin has sought assurances from his U.S. counterpart President Joe Biden during discussions last month that Ukraine won’t be admitted to NATO, as it sees any expansion of the western military alliance further eastward as a security threat. Biden refused to give such assurances.

Speaking to ABC News in the U.S. on Sunday, Secretary of State Antony Blinken said he doesn’t expect to see any progress in relations with Russia as long as tensions on the Ukraine border remain high.

“If we’re actually going to make progress in these talks starting next week, but I don’t think we’re going to see any breakthroughs next week, we’re going to listen to their concerns, they’ll listen to our concerns and we’ll see if there are grounds for progress. But to make actual progress, it’s very hard to see that happening when there’s an ongoing escalation,” Blinken said.

He added that “Russia has a gun to the head of Ukraine with 100,000 troops near its borders” and could increase that number of troops at short notice. “So, if we’re seeing de-escalation, if we’re seeing a reduction in tensions, that is the kind of environment in which we could make real progress and, again, address concerns, reasonable concerns on both sides.”

The world is watching how talks progress for any signs of a thawing in frosty relations between the U.S. and Russia.

Tensions have risen greatly, and across a number of fronts, since Russia’s annexation of Crimea from Ukraine in 2014, interference in the U.S. election in 2016, role in a nerve agent attack in the U.K. in 2018 and the creation of the Nord Stream 2 gas pipeline between Russia and Germany, among other issues.

The United States and its allies will raise election interference, arms agreements, Ukraine and other issues at security talks with Russia, White House spokeswoman Jen Psaki told reporters last Wednesday.

Speaking to reporters at a White Houses briefing, Psaki said “Russia has, of course, raised … the issue of European security. Let’s be clear: Over the past two decades, it is Russia that has invaded two neighboring countries, interfered in many other elections … used chemical weapons to attempt assassinations on foreign soil, and violated international arms control agreements.”

“We and our allies will be raising those issues and other issues with Russia in the days and weeks ahead, and certainly as a part of these talks. And of course, we cannot forget that there is an ongoing Russian military occupation in Ukraine,” she noted, referring to the ongoing conflict in the Donbass region of east Ukraine where pro-Russian troops have been fighting Ukrainian forces for a number of years.

The security discussions taking place Monday are the first talking point this week in a series of meetings between Russia and the West, with talks set to continue on Wednesday between the Russia Council and NATO in Brussels, and at a session of the Organization for Security and Cooperation in Europe in Vienna on Thursday.

How Biden manages Russia, and his Russian counterpart, is being closely watched with Fred Kempe, president and chief executive officer of the Atlantic Council, noting Monday that this week of talks “may be the most important week for Biden in his entire presidency from a foreign policy perspective.”

“Europe’s history knows despots threatening against more benevolent actors. We’ve seen this picture before. But we have to remind and show who really is the aggressor here. It’s an information game but at the same time Putin really can take military action if he wants to. We are really on the cusp of war. If he wants war to happen, Putin can make it happen. It would hurt Russia terribly, it would hurt Europe irretrievably,” he told CNBC’s Capital Connection on Monday.

Not everyone is so pessimistic about the prospects for the talks, and for wider Russia-Western relations.

Christopher Granville, managing director for Political Research at TS Lombard, told CNBC Monday that there was a precedence for agreement over curbs to military deployments in Europe, namely several accords signed in the Gorbachev-era during the final years of the Cold War.

One such agreement that was signed in 1990, the Conventional Armed Forces in Europe Treaty, covered arms control and contained specific provisions and limits on regional deployments, with Granville arguing that such an agreement could be reached again.

“If the sides can agree that they’re not going to do advanced deployments either close to Ukraine on the Russian side, or close to Russia on the Western side then you could have a deal. It has been done before, why could it not be done again,” he told CNBC’s “Squawk Box Europe” on Monday.

“Well, the answers are, I suppose, that the atmosphere is absolutely toxic, there is zero trust and everyone dislikes each other but stranger things have been seen and it’s been done before and I think the upside is being underestimated.”