Zarqawi's network was in Europe long before Iraq. Europe is his center of gravity, not Iraq. He projected his force into Iraq from Europe and regional countries, not vice-versa. That is why the order to take the network's activities to America in one of the last UBL tapes is a logical culmination of the AQ post-9/11 strategy.
Zarqawi is a longtime global terrorist and a longtime (pre-9/11) AQ WMD chief who set up shop in Iraq right before the war in anticipation of it (that is why Powell made Zarqawi central in his pre-war WMD case before the UN).
Saddam was harboring the AQ chem/bioweapons leader (or looking the other way as does Iran now). Zarqawi is/was not a regional or local thug who is/was trying to go global. All he had to do is take the feeder networks and channel some of them in the other direction. Even before the war, he made Iraq his "boot camp". Take a relatively educated European Muslim (who, incidentally, may look more "American" than "Arab"), give him a baptism of fire in Iraq, and if he survives and proves himself, he is ready for the greater task back home in Europe and possibly even deadlier ones in America.
The Zarqawi network has abandoned its strategic ambiguity and openly placed itself under UBL/Zawahiri/AQ authority. The utility of the plausible deniability of a separate organization had outlived its purpose. Just as in Iraq, new groups seem to pop up with new names every week to take credit for attacks, but the names don't mean anything, they are all cut from the same cloth, "Tawhid and Jihad" and "al Qaeda" (and whatever the next group calls itself) are six of one, a half dozen of the other.
Jihad is a global movement which has many surprising coalitions. Qaeda is just the "foundation" on which it started, but it is not so much the apex of an organizational hierarchy with lines of authority as it is the original "brand name" for an expanding global revolutionary movement. Like the early call a century ago to global socialist revolution, organizations in global Jihad spring up internationally and sometimes autonomously to advance the ideology. But just because they operate independently does not mean that they are divided.
For some reason, if someone says the "Bin Laden" network (or "al Qaeda") is attempting to launch an attack here, folks man the barricades.
But if you say that the "Zarqawi network" (or "Tawhid and Jihad") is attempting to launch an attack here, it sounds a bit ludicrous and not worthy of alarm.
Isn't that the point?
I plan on focusing on the continued expansion of the global Islamist insurgency in grad school, and have written several papers about it in the past.
I put a few of the papers on my site, but never linked them from here. The following was written for a National and International Security class, last December.
Good post.