US Vice President Mike Pence travels to Eastern Europe on Sunday to meet with important US allies.

The visit -- with a subtext focusing on the future of US-Russia relations under the Trump presidency -- will see stops in Estonia, Georgia and Montenegro from Sunday to Tuesday, comes in the wake of the US Senate and House of Representatives votes this week to impose new sanctions on Moscow.

In the aftermath of the votes to impose further sanctions on Russia, some in Europe expressed concern that rather than forcing the Kremlin to fall in line, sanctions could create further tensions across the continent and especially in Eastern Europe.

Key agenda items in Pence's trip include a visit to see US and Georgian troops participating in the Noble Partner NATO-related exercise which also features troops from the United Kingdom, Germany, Turkey, Ukraine, Armenia and Slovenia. And the vice president will also participate, in Montenegro, with leaders across the western Balkans in the Adriatic Charter summit.

The immediate backdrop for Pence's visit is the continuing controversy over Russia and the Trump campaign team. After the sanctions bill votes, it now falls on Trump to decide whether he will sign it into law or, in what would be a remarkable move, veto it.

The legislation, which would impose restrictions on oil and gas projects in Russia and hit the country's economy, has been condemned by Russian Deputy Foreign Minister Sergei Ryabkov, who asserts it would plant a "dangerous mine" under bilateral relations that could explode in coming months.

Trump's decision on this issue will be watched closely not only in Moscow, but also in Eastern Europe, which will add to the spice of Pence's various meetings in coming days.

Part of the nervousness that key US allies have about the President's positioning on Russia is what it could mean for US commitments in the region and NATO.

Trump has already flip-flopped on this issue, describing the military alliance last year as "obsolete" -- then claiming that since he criticized it, that money has been "pouring in" from other allies making it no longer obsolete. While his alteration in tone was welcomed, the fact his mind on such a fundamental issue could be so easily changed is not entirely comforting to those who feel the heat from Moscow's proximity.

On top of the reversal in defense spending cuts across the alliance, a new European Defence Action Plan was agreed earlier this year that will see greater continental military cooperation.

For Trump, the key strategic question now on Russia is whether recent developments have destroyed the opportunity that may have existed for a warming of relations between Washington and Moscow.

The President has previously given multiple indications that he believes Russia is not a serious threat to the US, hinting in January that he could even drop existing economic sanctions if the country "is helpful." Specifically, he appears to believe there were multiple common interests over issues such as preventing Iran secure nuclear weapons and combating international terrorism.

But his proposed repositioning of relations with Russia now looks for the time being to have been put on ice.

Should Trump be forced to sign the sanctions legislation, Pence's visit should help calm America's allies and reassure them that the US still has an interest in defending their values.

However, talk from Moscow of retaliation and reserving "the right for reciprocity and other measures that may affect the interests of the US" will concern some smaller nations in Russia's so-called "sphere of interest."

And any breakdown in relations with Russia would, potentially, have significant implications for relations between Moscow and Washington in other areas of the globe, including the Syrian conflict.

As unpalatable as Syrian dictator Bashar al-Assad having a role in the country's future governance might be for some Western countries, when the US and Russia are in open dispute over Syria, the prospects for reaching a lasting political settlement become bleaker, and the regime may even feel emboldened to commit further atrocities.

As Pence prepares for his trip to reassure America's allies, Trump now finds himself in a big bind over Russia. Despite his desire for warmer relations, the Senate and the House may have closed that window. Yet the legacy of his warm rhetoric toward Moscow has made his traditional allies in Eastern Europe understandably jumpy.

It's hard to know exactly how the President will move forward now, but nothing can be taken for granted. Trump already has the reputation for making unpredictable foreign and defense policy decisions when he has been backed into a corner at home. His political inexperience and ad hoc style of governing means this cannot be ruled out again now, as he faces multiple crises in DC.