According MagPul's website for the CTR & the MBUS:

EXPORT NOTICE: This product and/or its components is subject to the International Traffic in Arms Regulations (ITAR, 22 CFR Parts 120-130) and export is strictly prohibited without authorization or a license issued by the U.S. Department of State's Directorate of Defense Trade Controls.
Additionally, any documents or engineering drawings, prints, etc. that can be viewed, downloaded, or printed from our Web site may contain technical data which may not be exported outside of the United States, or released or disclosed to non-US persons (i.e. persons who are not US citizens or lawful permanent residents) inside of the United States, without prior written authorization by the relevant US Government agency.
Violations of these export laws are subject to severe civil, criminal and administrative penalties.

Also at another location on the site:

Magpul Industries Ecommerce

DO YOU SHIP INTERNATIONALLY?
We do NOT ship internationally and all orders must have both billing and shipping addresses located within the 50 United States or District of Columbia. The only exception to this is for shipments to APO/FPO addresses, with important restrictions as noted below:

PLEASE NOTE: Many of the items on this Web site are subject to the International Traffic in Arms Regulations (ITAR, 22 CFR Parts 120-130), the Arms Export Control Act (22 USC 2778), or the Export Administration Act of 1979 (as amended, 22 USC App. 2401 et. seq.) and EXPORT IS STRICTLY PROHIBITED without authorization or a license for each order as issued by the U.S. Department of State's Directorate of Defense Trade Controls.