This news has been spreading throughout Japan and sellers are scrambling to ship packages before the deadline. If you are in the process of buying a strop or a whetstone or anything that will weigh over 16 ounces, you better buy now.
Source
Source
Attention to US customers: Due to the recent threat of terrorists against United States and thereby the reinforcement of aero safety by the US government, Japan Post has accounted that it would stop shipping packages over 453g(16oz) to United States including US territories such as Guam and Saipan effective November 17th. This includes EMS, Airmail, and SAL packages and it will affect estimate of over 200,000 shipments a month. According to the Ministry of Land, Infrastructure, Transport and Tourism, this treatment intend to limit the number of packages with unknown senders and unclear item contents that are shipped to United States and this will last at least 1 month.