The United States and a number of its Western partners have expressed their great apprehension&nbsp;regarding the rapid growth in Russian arms exports to a number of longstanding Western military clients, and in particular to the proliferation of advanced anti aircraft weapons and anti access area denial (A2AD) weapons systems which seriously threaten Western strategic interests. The United States has responded with a concerted campaign to undermine Russian arms exports, both to prevent the proliferation of weapons systems which could serve purposes contrary to Western strategic interests and to reduce Russia’s market share in the global arms trade - cutting Moscow off from a valuable source of income. One key means of undermining Russian arms exports has been the threatening of states making large acquisitions of Russian arms with economic sanctions - with potential clients for advanced Russian made air defence systems in particular threatened with severe consequences should they purchase such weapons. Sanctions are applied under the Countering American Adversaries Through Sanctions Act (CAATSA), signed into law by President Donald Trump on August 2nd 2017, under which states purchasing Russian, North Korean or Iranian weapons systems are liable to suffer reprisals for their acquisitions. A number of states including Iraq and Turkey have been threatened with sanctions should the follow through with plans to acquire Russian S-400 air defence systems - and several others are set to follow. The United States’ use of CAATSA to punish Russian arms clients could well have severe implications for a number of Washington’s emerging partners, most notably India which is a longstanding client for Russian arms. Russia is by far the largest source of arms for the Indian military, and Russian and Soviet made weapons comprise over 70% of the country’s inventory. While India has emerged as a growing U.S. partner in South Asia in recent years, and has in the last decade significantly increased its imports of U.S. arms, America’s new policy towards Russian military clients could have severe implications for Washington’s budding relationship with Delhi. India has notably never responded will to foreign interference in the country’s foreign policy affairs, most recently refusing a U.S. request to cut diplomatic and economic ties to North Korea. As a founding member of the Non Aligned Movement, Delhi has long stood closely by its policy of refusing to position itself in either the Western or the Russian/Soviet bloc. India is reportedly imminently set to purchase the Russian made S-400 Triumf air defence system, the proliferation of which the United States has notably had a particularly low tolerance for. The deal for the weapons system’s acquisition is set to be finalised when India’s Defence Minister Nirmala Sitharaman makes her first trip to Moscow. If the United States is to apply policy consistently has it has to other potential clients for the S-400 and other large Russian weapons packages, it would require Washington to impose sanctions on Delhi for supporting Moscow’s defence industries and thus aiding an American adversary. India is, for a number of reasons, highly unlikely to abandon its plans to acquire the S-400 and future Russian weapons systems due to threats of American sanctions however. The first is the importance of the S-400 system to India’s defence, as the platform is truly without equal particularly in its anti aircraft and anti stealth capabilities - which India today needs more than ever as an asymmetric response to neighbouring China’s growing stealth fighter fleet. The second is that India remains unable to quickly terminate its defence partnerships with Russia even if it did intend to do so, as cooperation with Moscow has brought Delhi extensive benefits for several decades and the country’s reliance on Russian arms remains extremely high. As former Defence Minister Arun Jaitley stated in 2015 “India and the Russian Federation enjoy a special and privileged strategic partnership. Russia has been our long standing and trusted defence partner and Government is committed to&nbsp;continuing the relationship to&nbsp;the mutual benefit of&nbsp;both countries.” With India set to purchase the S-400, Washington could well risk seriously compromising a growing defence partnership with a key strategic partner and putting multi billion dollar potential weapons sales to India at risk. As Cara Abercrombie, a U.S. Defence Department official and expert on U.S.-Indian military ties, stated, Delhi's acquisition of the S-400 was put the two countries on a "collision course." She advised exempting India from sanctions under CAATSA in order to preserve positive relations with the United States' emerging regional partner. A souring of relations is inevitable should the United States remain consistent in its policy an apply sanctions to India under CAATSA, and would represent a significant strategic loss for the United States. On the other hand should Washington choose to exempt India from sanctions, it could further alienate both longstanding American strategic partners and non aligned states alike across the world such as Turkey, Iraq, Saudi Arabia, Qatar, Egypt, Morocco and Indonesia among others. These states have all signed major contracts for Russian arms and are either set to acquire or are considering the very same S-400 system, and should they be subjected to economic punishment where Delhi is exempt Washington’s double standards in applying CAATSA sanctions would appear blatant. Ultimately with the United States seeking improved relations with a number of longstanding Russian arms clients due to pressing strategic needs, Vietnam and Indonesia being two other notable cases, similar dilemmas are set to reoccur and leave Washington to choose between arbitrary exemptions or the compromising of critical emerging strategic partnerships. CAATSA may well serve to seriously hinder Washington’s strategic interests overall, and a abandoning of the policy of imposing sanctions on Russian arms clients, perhaps restricting applications to North Korean and Iranian clients alone, could well be the only means for Washington to prevent what could well become a serious crisis in relations with a number of its strategic partners.