In my opinion it's a lot like the posturing of the Axis powers before WW2. Before the Second World War officially started, the Axis countries of Germany, Italy and Japan were fighting far off conquests in Africa, Asia and the Pacific. The Germans occupied some of their neighbors, the Sudetenland and then Czechoslovakia. The Invasion of Poland is what started WW2 in Europe. It took two more years for the Japanese to drag the US into it.
The US and it's allies have been on a campaign in the middle east and central asia, dabbling in North Africa and Egypt and now eying Syria. Russia has revisited it's old neighbor Ukraine. What will be the occupation or annexation that officially starts WW3?