A fascinating item from today's subscription-only National Journal, presented below with the hopeful acquiescence of the fine NJ editorial team. The author is Marisa Katz.

Barack Obama is losing his top foreign-policy adviser to active military duty. Mark Lippert, who has helped to write every major Obama foreign-policy speech and is known as “an expert at nailing down details,” has been called up by the Naval Reserve. He’s in training now but says his orders don’t specify where or how long he’ll deploy. This will be the first tour for the lieutenant junior grade, who signed up for the Reserve about three years ago.

Obama’s office has yet to formally announce a successor, but Obama advisers say that Denis McDonough, a Latin America specialist and onetime foreign-policy adviser to then-Senate Democratic Leader Tom Daschle, is stepping up his involvement in Lippert’s absence.

Lippert, 34, received his master’s in international policy from Stanford University and joined Obama’s office after five years on the Senate Appropriations panel’s Foreign Operations Subcommittee. He accompanied the senator on his three international trips and helped to formulate his positions on issues as diverse as aid to Africa and policy toward Israel. “He’s able to get inside the senator’s head,” said Dan Shapiro, Middle East advisor to the Obama campaign. “He always has a pretty clear and accurate sense of what the senator’s views would be and what type of language he would be comfortable expressing those views with. He’s like an alter ego.”

Of course, the foreign-policy issue that has overshadowed all others is Iraq. Obama supports a “phased redeployment” of American troops, and his campaign homepage boldly declares, “The war in Iraq should never have been authorized, never have been waged, and it must end now.” Lippert had a hand in that position, too. In his book The Audacity of Hope, Obama writes about visiting Iraq with Lippert, who at one point asked a senior U.S. military officer “what he thought we needed to do to best deal with the situation.” Obama had been out of earshot. “What did he say?” he later asked his aide. “Leave,” Lippert replied.

Other Obama foreign-policy advisers acknowledge that Lippert’s departure is a significant loss. Shapiro called him “an incredibly valuable part of Sen. Obama’s team.” Samantha Power, a human-rights scholar and Pulitzer Prize-winning author, said she was particularly impressed by Lippert’s “rigor.” She added, “He really pushes back on every idea, forces you to get your game up, brings the best out in the people he’s coordinating.”

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.