I think "even as" and "although" are not exactly synonymous. "even as" connotes strongly that the action is still in process, whereas "although" is more neutral in that the process could have already been completed or not and is more dependent on its context to decide which.
I think the sentence as written is a shortened form of:
The Pentagon is sending several thousand more marines than (they) originally planned (to send) to Iraq next year.
Since the ellipses do not cloud the meaning, IMO, it is a proper comparison.
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993