Well they have done it in the past... not sure why these would be any different.
http://www.ar15.com/archive/topic.html?b=3&f=12&t=599935
The GCA created what is known as the "sporting purposes" standard for imported firearms, saying that they must "be generally recognized as particularly suitable for or readily adaptable to sporting purposes." GCA sporting purposes includes hunting and organized competitive target shooting, but does not include "plinking" or "practical shooting" (which the ATF says is closer to police/combat-style competition and not comparable to more traditional types of sports), nor does it allow for collection for historical or design interest.[19][20]:16-18 Hence, foreign made assault rifles and machine guns such as the AK-47, the FN FAL or the Heckler & Koch MP5 could no longer be imported into the United States for civilian ownership (however, semi-automatic models of the same weapons were permitted until the definition of sporting purpose was further tightened in 1989). The fact that domestic production and sale of weapons identical to those prohibited from import remains legal under 18 U.S.C. 922(r), without any need to conform to the sporting purposes standard, has also led to criticism that the GCA is more a matter of economic protectionism for the benefit of U.S. firearms industry than a genuine effort to curtail gun violence.
18 U.S.C. § 922(r)
It shall be unlawful for any person to assemble from imported parts any semiautomatic rifle or any shotgun which is identical to any rifle or shotgun prohibited from importation under section 925(d)(3) of this chapter as not being particularly suitable for or readily adaptable to sporting purposes except that this subsection shall not apply to -
(1) the assembly of any such rifle or shotgun for sale or distribution by a licensed manufacturer to the United States or any department or agency thereof or to any State or any department, agency, or political subdivision thereof; or
(2) the assembly of any such rifle or shotgun for the purposes of testing or experimentation authorized by the Attorney General.
27 CFR 478.39 - ASSEMBLY OF NON-SPORTING SHOTGUNS AND SEMIAUTOMATIC RIFLES FROM IMPORTED PARTS
(a) No person shall assemble a semiautomatic rifle or any shotgun using more than 10 of the imported parts listed in paragraph (c) of this section if the assembled firearm is prohibited from importation under section 925(d)(3) as not being particularly suitable for or readily adaptable to sporting purposes.
(b) The provisions of this section shall not apply to:
(1) The assembly of such rifle or shotgun for sale or distribution by a licensed manufacturer to the United States or any department or agency thereof or to any State or any department, agency, or political subdivision thereof; or
(2) The assembly of such rifle or shotgun for the purposes of testing or experimentation authorized by the Director under the provisions of Sec. 178.151; or
(3) The repair of any rifle or shotgun which had been imported into or assembled in the United States prior to November 30, 1990, or the replacement of any part of such firearm.
(c) For purposes of this section, the term imported parts are:
(1) Frames, receivers, receiver castings, forgings or stampings
(2) Barrels
(3) Barrel extensions
(4) Mounting blocks (trunions)
(5) Muzzle attachments
(6) Bolts
(7) Bolt carriers
(8) Operating rods
(9) Gas pistons
(10) Trigger housings
(11) Triggers
(12) Hammers
(13) Sears
(14) Disconnectors
(15) Butt stocks
(16) Pistol grips
(17) Forearms, hand guards
(18) Magazine bodies
(19) Followers
(20) Floor plates