A little note from The Guardian explains:

The Bush administration is planning a test run of America’s emergency military call-up, stoking speculation about a return to a draft at a time when the White House is considering sending more troops to Iraq.

[…]

…Jim Nicholson, the secretary for veteran affairs, said he believed “society would benefit” if the US were to bring back the draft.

In an indication of the sensitivities surrounding the draft, the White House moved to counter the remarks. He withdrew his statement hours later.

What emergency conscription system, you might ask?

America suspended the draft in 1973 during the last months of the Vietnam war. But it has required all males to register for the draft since 1980, keeping its vast system of draft boards on standby.