I wouldn't call it economic dependency. Economic sweetener seems more appropriate. While indeed the US economy is subsidized to the tune of $1.3 trillion per year (roughly twice the Pentagon's annual budget), it's important to note that the lion's share of capital flowing into the US economy is private. So whereas Merkel can't say "I'm not going to support US deficits" in order to keep the money in Germany, she can say "I do want the Pentagon to sign a € 2 billion contract with Siemens".
Also, if you take a look at how the negotiations unfolded (see Migeru's post), Merkel was initially against deployment of the sites in Poland & CzRep. only to be swayed in favor later, after negotiations... or arm twisting. You wouldn't expect that from someone who believed in the Atlantic partnership.
To conclude, I think that large contracts are definitely in the play.