New York (CNN) -- A lesbian cadet who left the West Point Military Academy has been denied readmission, just as the U.S. military begins changes mandated by a repeal of the "don't ask, don't tell" policy.
The 17-year-old policy, which prevented openly gay and lesbian personnel from serving in the armed forces, was repealed in December.
But officials at the prestigious military academy in New York say they could not readmit Katherine Miller, who had performed "exceptionally well academically, militarily and physically," because of uncertainties concerning when the new policy will take effect.
"While the 'don't ask, don't tell' policy was recently changed and will be repealed, the effective date has not yet been determined," academy spokesman Lt. Col. Sherri Reed said Wednesday. "Due to this situation, West Point is unable to offer her readmission as current DADT policies remain in effect."
Miller left the academy in August 2010 after revealing she was a lesbian, but reapplied in anticipation of the repeal.
"Although I am deeply saddened that I will not be readmitted to West Point, I understand and respect the decision," Miller said in a statement. "The Academy and the military are required to abide by a strict DADT repeal implementation timeline, and readmission would violate that timeline."
Daniel Choi, a West Point alumnus and openly gay soldier who served in Iraq, condemned the decision.
"It is remarkably disappointing that our academy rejects leadership and initiative at such a critical and historic moment for the nation it serves," said Choi, who was discharged after revealing he was gay.
Reed said Miller could again seek readmission once the repeal process is completed.
Miller, now a student at Yale University, says she hopes to graduate and rejoin the military.
"I look forward to the day they deem it appropriate for me to put the uniform back on," she in the statement.
The announcement follows a landmark vote earlier this month when a three-person panel at Lemoore Naval Air Station in California voted unanimously not to discharge an openly homosexual sailor.
Meanwhile, officials say the military expects to be ready to implement the repeal of the policy by midsummer.
Earlier this month the Defense Department, under Secretary Clifford Stanley, told members of a House Armed Services subcommittee that the process will not be rushed "because we want to make sure that it's done right."
"At the same time, we don't want to take forever to do it," he said.
The announcement was the first time the Pentagon has set a target date for the military to be ready for a repeal of don't ask, don't tell.
President Barack Obama, Defense Secretary Robert Gates, and Joint Chiefs of Staff chairman Adm. Mike Mullen will ultimately need to certify that the Defense Department is ready for a repeal of the policy. At that point, a 60-day countdown would begin before the repeal is officially implemented.
A recent Pentagon study concluded that allowing openly gay or lesbian troops to serve in the military would have little lasting impact on the armed forces. Opposition to the change was much higher in Army and Marine combat units than in the military as a whole.