The Obama administration is stalling a congressional inquiry into its ongoing refusal to uphold a U.S. law that would sanction Russia for selling advanced missile systems to Iran, according to recent communications between the State Department and Congress exclusively obtained by the Washington Free Beacon.

President Obama has the authority under U.S. law to designate as illegal Russia’s recent sale to Iran of the advanced S-300 missile system, a long-range weapon that would boost the Islamic Republic’s military capabilities.

The administration has so far declined to exercise its sanction authority under law and has been stalling attempts by Congress to discern the rationale behind this decision, prompting accusationst hat the administration is ignoring U.S. law and “acquiescing” to the sale in order to preserve last summer’s comprehensive nuclear deal.

Rep. Steve Chabot (R., Ohio), who first launched an inquiry challenging the administration’s reluctance to sanction the sale in early April, told the Free Beacon that the White House is continuing to punt questions from lawmakers, jeopardizing efforts by Western nations to block the arms sale.

The administration informed Chabot on June 8—more than two months after his initial request—that it has not reached a determination as to whether it will move forward with sanctions as specified under the law.

Obama administration officials reiterated this stance when contacted by the Free Beacon late last week.

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