Russia and the EU each have a concern in the Ukraine as the country is on the very doorstep of both their boundaries but America is thousands of miles away so why it is holding talks and making threats is not easily obvious apart from the well worn fact that where there is a war, America is usually involved somewhere.
John Kerry is over here making threats of sanctions against the Russians if they don't keep to their side of the deal brokered over the last few days which isn't going down very well with the EU who is having a hard enough time with the faltering economy as it is without tinkering with their relationship of Russia largest export partner worth £292 billion annually to the EU.
Easy to see why the Europeans are wary of American led sanctions threatening their largest source of income, especially while America has less to lose as Russia are 15th in the list of countries the USA export to and here is where the murmurings from EU representatives are whispered, the USA is screwing the EU over.
The US is keen to see more sanctions on Moscow because the US has very little interest directly in Russia and are eager for the EU to pull back on its interests in Russia which would allow America to have a better chance to get in subsequently when relations improve and step in with replacement of what the Russian's provide to the EU and what the EU provide to Russia.
So while it seems that American involvement is just because America is always up for a bit of conflict, war and mayhem, it may also be to guide the EU away from Russia so it can replace it for its own economic benefit.
As the EU is not playing ball with America and talking down any idea of sanctions on Russia maybe the murmurings of the Americans using the conflict as an excuse to urge the EU to step back so it can step in have reached the ears of the decision makers who are now wise to it.