Ogged of Unfogged boils the importance of why we need to forge a "proud wartime liberalism" down to a simple nugget. Actually, it’s a commenter over at Political Animal who does this, and it’s about something, that at first glance, seems unrelated.
Call it the "Nixon in China" gambit. After 9/11, politics in America were turned upside down, and the parties’ stands on national security/terrorism became the deciding factor for a decisive number of voters, as a careful analysis of the vote will reveal.
Taking the Nixon gambit, this means that any Democrat wanting to succeed at the national level needs to risk appearing to be more aggressive than Republicans on national security issues, so that the scurrilous charge that we’re too weak, too soft to defend America can be successfully countered.
We already have some outstanding ways of dealing with this issue. But those solutions won’t get the airing they deserve until we can, at the very least, neutralize this line of attack.
Update: This doesn’t mean that liberals have to endorse our actions in Iraq. Quite the opposite–I think we need to continue making the argument that Iraq is sapping our ability to fight a viciously tough war against our enemies. But the fact is that our reluctance to embrace an aggressive position on national security issues (beyond "we’re not Dubya") prevents the argument from developing the force that it needs in order to be truly effective.