If you haven't noticed, the Republicans and their mainsteram media lapdogs are going to attack the Democrats as being "weak on national security" and "weak on terrorism" no matter what they do.
If they want not to be attacked at all, they should just stay completely out of politics.
Of course, they should pick their battles, and fight the ones that are really important. It's obvious from their inaction on and even outright support of the PATRIOT Act, that civil liberties just aren't that important to them, no matter what their rhetoric might be.
The same has been true regarding their "opposition" to torture, to the Iraq war, to Bush's Supreme Court nominees, their support of the "public option" for health care, etc. The Democrats have shown very little spine on these matters, when it comes time to walk their talk. And the public is noticing. That's why Congress has such a low approval rating, and why the shine is wearing-off Obama.
Their spinelessness and willingness to be the Bush-lite party could cost them dearly in the mid-terms and 2012. They're just lucky the Republican party is tearing itself apart with their "tea party" splintering and fighting over who are the "real conservatives".