Since President Trump handed off the decision on the Afghan War’s escalation to Defense Secretary James Marris, we’ve heard several wildly different figures from different sources, with some reports suggesting that an escalation of 3,000 to 5,000 was too small, and that Mattis might ultimately go much, much bigger.

In reality, however, officials now say that Mattis’ autonomy on the matter has its limits, and those limits are 3,900 more US ground troops. A classified memo is said to be in place which would oblige Mattis to get White House authorization if his escalation is to be any larger than that.

The Pentagon has declined to comment on the matter, noting the memo is classified, but some administration officials are said to have been surprise that any restrictions at all were placed on Mattis for deciding on troop levels in Afghanistan.

This probably explains why the official decision hasn’t been made yet on troop numbers there, as Mattis was often rumored to be leaning toward the high end of the 3,000-5,000 range, and may still be trying to get the administration to sign off on that.