Gates has been careful not to estimate how much time that may take.
Obama vowed to repeal DADT during his State of the Union address this year. In February, Gates and Mullen testified before the Senate Armed Services Committee that they both personally believed that the 17-year-old law should be repealed and announced that the Pentagon would undertake a long-term study into how best to implement repeal.
The review was released on Nov. 30. The Senate had already tried and failed to pass a defense spending bill with repeal attached over the summer, but it was again blocked by Republicans this month who wanted more amendments on the massive bill.
Advocates hoped that the review, which concluded that DADT could be repealed with limited effects on morale and readiness, would garner enough extra votes from both sides of the aisle to break any filibuster. They got an extra boost when Gates pleaded for the Congress to pass repeal, warning that his "greatest fear" would be an abrupt, court-ordered repeal.
There were still some hurdles. Sen. John McCain (R-AZ), ranking member of the Armed Services Committee, fashioned himself into repeal's most vocal opponent, leading filibusters and scoffing at the Pentagon review. Some of the service chiefs told the committee that they recommended against repealing DADT now, although they acknowledged that their branches could and would implement it if so ordered.
Repeal, which was still attached to the defense spending bill, then got caught up in the whirlwind of lame duck legislation. Republican senators vowed not to vote for any bill before tax cuts and a government spending bill were passed. When Senate Majority Leader Harry Reid brought it to the floor anyway, Sen. Susan Collins (R-ME), a repeal advocate who had been negotiating with Reid for days, balked. Collins argued that Reid was still not allowing enough amendments to the bill.
It failed, and it seemed, briefly, like the Congress had lost its chance at repeal. But Sen. Joe Lieberman (I-CT) and Collins decided to submit a standalone DADT repeal bill, using the same language that was in the defense authorization.
That was on Dec. 9. On Dec. 15, the House, which had already passed the defense spending bill, passed that standalone easily. On Dec. 18, a handful of Republican senators broke their promises to caucus leaders that they'd vote against legislation until a spending bill was passed and voted to break McCain's filibuster. Repeal passed.
It remains to be seen how long it will be until DADT is truly repealed. But today, the process will begin.