Dunford presented the current planned "residual force" as 200, saying that this hadn't changed since February. The US announced 200 would stay on February 21, but on February 22 officially increased that number to 400.
It's not clear from Dunford's statement where the "incorrect" aspect of the new report, which came out of a Wall Street Journal, exists. That report suggested that the 1,000 figure was not yet finalized, but was being discussed. Dunford's comments didn't include any details on what is actually being discussed, but just that nothing was finalized.
This could mean the calls for more troops, doubtless coming from administration hawks, aren't the slam dunk the Wall Street Journal is presenting them as.
It could, on the other hand, mean the administration isn't ready to announce the new figures publicly yet, and will just insist the media is lying until some future date when it is more convenient to make the numbers official.