Russians position missiles in the Atlantic capable of striking eastern cities. Actually given the technology today each of the major powers/Nations possesses weapons that could destroy, 10 times over, their adversaries and given the advances in weapons there is not the need to position them close to the land(s) they would strike.
There are ballistic submarines, belonging to several nations, patrolling the oceans that each have the capability to unleash more firepower than was most likely used in World War II alone. Then there are land-based, and soon no doubt, space-based, missiles that could be programmed or ordered to drop onto certain locations as directed by the nations who control them. In the world today, as it stands, certain weapons have the capability to create such destruction that the use of them alone crosses a dangerous threshold that could create a world that soon could be inhabitable or at least one that would fail to support whoever was left to contend with the aftermath.
Often times it's as easy as the statement that when you have two bullies on the same block that eventually they are going to fight regardless. I hope that reasoning never comes to fruition with respect to today's governments given the nature of the weapons that each possesses. You would think when the Soviet Union fell apart and they saw that the rest of the World didn't swoop in and seek to take them over that they would not continue as if NATO and the West was their chief adversary. Today you have a resurgent Russia building up their military with seemingly sole desire and the goal being to defeat or destroy America and "The West". Also far different than years past is a resurgent China which before was seemingly content with having a military to ensure the protection of their own nation. Today the Chinese are apparently seeking to create a military to project their power and influence worldwide and far outside their own borders. If that is the case then it is feasible that future conflict is inevitable but potentially as long as there is the mutual assurance of total destruction then maybe calmer heads will prevail. The real danger comes in when one leader is suicidal and/or mentally unstable or when one side actually believes such global conflict is winnable and survivable.
One thing is fairly certain and that is in a world such that weapons of mass destruction as we have today the only way to win is not to use them at all and if such weapons are ever used in large-scale conflict then the fortunate ones will likely be the ones that are taken out first and are not left to contend with the aftermath of what would surely be a horrible place to live in.