I s there anyway that his citizenship canbe revoked. Obviously, he lied when taking his oath for citizenship.
8 USC § 1451 - Revocation of naturalization
(c) Membership in certain organizations; prima facie evidence If a person who shall have been naturalized after December 24, 1952 shall within five years next following such naturalization become a member of or affiliated with any organization, membership in or affiliation with which at the time of naturalization would have precluded such person from naturalization under the provisions of section 1424 of this title, it shall be considered prima facie evidence that such person was not attached to the principles of the Constitution of the United States and was not well disposed to the good order and happiness of the United States at the time of naturalization, and, in the absence of countervailing evidence, it shall be sufficient in the proper proceeding to authorize the revocation and setting aside of the order admitting such person to citizenship and the cancellation of the certificate of naturalization as having been obtained by concealment of a material fact or by willful misrepresentation, and such revocation and setting aside of the order admitting such person to citizenship and such canceling of certificate of naturalization shall be effective as of the original date of the order and certificate, respectively.
(a) A person who is a national of the United States whether by birth or naturalization, shall lose his nationality by voluntarily performing any of the following acts with the intention of relinquishing United States nationality—
snip(7) committing any act of treason against, or attempting by force to overthrow, or bearing arms against, the United States, violating or conspiring to violate any of the provisions of section 2383 of title 18, or willfully performing any act in violation of section 2385 of title 18, or violating section 2384 of title 18 by engaging in a conspiracy to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, if and when he is convicted thereof by a court martial or by a court of competent jurisdiction.
So, yes, there is a way to do so...legally.