Since the beginning of his term and as recently as three weeks ago, Mayor Bill de Blasio said the NYPD needed no more cops. In fact, he did not include any funds for additional officers in his budget.

Suddenly last week, he said the department would hire an additional 1,297 officers -- 297 more than the 1,000 extra cops sought by City Council Speaker Melissa Mark-Viverito.

The day the deal was announced, de Blasio explained that there were long conversations recently about more officers. He added that the talks led "us to strengthen our police force while encouraging a deepening of reform, while finding key reforms on the fiscal front."

The statement provides no specific answer.

I take no position on whether the hiring is good or bad for the city. What is not good for the city is a mayor whose word cannot be believed. His reversal is puzzling because he repeatedly rejected arguments by Commissioner Bill Bratton for new cops. De Blasio opposed an increase in the rank and file, even after Bratton specified how they would be utilized: about 300 for full-time counterterrorism duty, another 300 for "community policing," as envisioned by Chief of Department James O'Neill.

Bratton had said he expected to get additional officers, though he never specified a figure. At Police Plaza, the word is that a deal probably had been in the works, and that despite the mayor's denials, NYPD officials expected the number to be between 600 and 1,000 new officers.

So how did the mayor agree to the 1,297? City Hall has said nothing beyond what the mayor offered last week. Bratton brushed off the question about the new officers when asked last week, and no one at Police Plaza has been able to explain it, either.

Some outside the NYPD suggest the mayor yielded to Mark-Viverito so that she, rather than he, could take credit (unlikely) or that he was outfoxed by Bratton (unlikely, but possible).

The most favorable explanation for de Blasio came from a top department official who said that City Hall had pushed the NYPD to be more specific about its needs until the department articulated programs the mayor could accept.

Still, the official said he could make no sense of the mayor's long-standing claim that the department needed no more officers.