Mention "Recep Tayyip Erdogan" to a U.S. national security official. Chances are, you will see a few eye rolls

The Turkish president has made a name for himself as a brash nationalist who is more than willing to tug at Russian President Vladimir Putin’s sleeve for advanced weaponry despite his country's membership in NATO. Turkey’s deployment of the Russian-manufactured S-400 missile defence system continues to hamper Ankara’s ties with Washington.

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Indeed, it affects nearly every conversation U.S. officials have with their Turkish counterparts. Despite seeing Turkey’s defence procurement agency cut off from the U.S. financial system as punishment over the S-400, Erdogan has no intention of backing down.

But Turkey is hardly the only country with U.S. ties exploring the S-400 system. India, a key player in the Biden administration’s pivot to the Indo-Pacific, has already forked over hundreds of millions of dollars for S-400 batteries. And while the Russians haven’t yet delivered the system, there is a significant possibility New Delhi could be on the receiving end of U.S. sanctions, just like Ankara and Beijing. The United States and India are reaching a point of confrontation.

By law, the U.S. has to sanction any country that engages in a "significant transaction" with the Russian defence and intelligence sectors. This provision of the 2017 Countering America’s Adversaries Through Sanctions Act (CAATSA ) was passed to punish Moscow for its 2014 annexation of Crimea.

But the law includes a presidential waiver, so the Biden administration faces a dilemma. It can grant India a waiver and thereby allow Russia to collect cash from a lucrative defence deal. Alternatively, Washington can sanction India and potentially throw a wrench into the Quad group.

The Biden administration has given little indication of what it intends to do. The State Department insists no decision has been made on the issue. This is partly because the S-400’s are not yet on Indian soil. During his visit to New Delhi this March, Defence Secretary Lloyd Austin acknowledged that, hypothetically speaking, acquiring the S-400 would be considered a significant Russian defence purchase and, therefore, sanctionable.

Even so, it’s not like India buying Russian defence equipment is a new phenomenon. The Indian military has relied on Russian hardware for decades. Between 2016-2020, India was the largest recipient of Russian arms, making up 23% of Russia’s total exports. Jeopardizing the U.S.-India strategic relationship over an arms deal would seem like an overreaction, particularly given this history.

As Sameer Lalwani and Tyler Sagerstrom of the Stimson Centre wrote in War on the Rocks last month, "If a partnership with India is 'vital' to greater regional burden-sharing and balancing, sabotaging relations with India would be, on net, counterproductive."

In other words, sanctioning India to prevent the Russians from profiting off a few billion dollars would be the foreign policy equivalent of cutting one's nose off to spite one's face.