It is not entirely fair, or for that matter accurate to simplify a globally integrated economy down to simple imperialism, therefore the following is very small part of what we are currently facing:
Global integration makes a lot of sense in the lens of capitalist growth. The traditional theory of imperialism holds, namely that domestic capital in advanced countries has fully saturated home markets and needs to find both new markets and/or cheaper sources of raw materials to increase profitability.
What is unique about the current period (and would be unique to any period of capitalist development) is the level of technology in the "home" nations.
Higher levels of technology by definition require larger capital investments, and ever increasing freedom/complexity of financial markets in order to facilitate these investments (and to get profit out of the colony).
As we are at the highest level of technology thus far in human advancement, modern imperialism requires the highest level of capital investment and most advanced financial markets the world has ever seen to be successful. All of this is fairly obvious and mundane.
Where this point becomes more interesting (to me at least) is that with greater levels of capital investment, (higher levels of development) it is easy to argue that greater levels of military security should also be a priority. This will come as no surprise to the portions of the world who live under perpetual occupation of the American military.
The two large contradictions here are that, 1. The very capitalists who rely on their home state for unprecedented military security are more often than not advocates of a shrinking the state at home (as the larger the state the more of their domestic profits are necessary to sustain it). And 2. The very same high level of technology that precipitates the need for military security in colonies (or subjugated nations, or whatever the popular thing is to call the countries we are fucking over today is), allows for easy destruction of large capital investments by small groups of unhappy, or aware citizens of these nations (ie "terrorism"). Technology facilitates the easier destruction of technology.
As per the development of any system, modern global capital holds within itself contradictions that have the potential to be its undoing.