It's being reported that back in mid November, the General Services Administration (GSA) began construction work on the George P. Shultz National Foreign Affairs Training Center (NFATC) Child Care Center and a new security fence. As I noted in this post from last April that means closing a ~2,000 foot long trail from South George Mason Drive to South Quincy Street (see below). The master plan was approved by the NCPC in June.
The trail doesn't get a lot of use, but y'know, it's a step backwards in the name of security. So long trail, we hardly knew you.