The US government has voiced additional concerns about India's planned procurement of Almaz-Antei S-400 Triumf self-propelled surface-to-air missile (SAM) systems from Russia.

Speaking at a recent US House of Representatives foreign affairs subcommittee, US Principal Deputy Assistant Secretary for South and Central Asia, Alice Wells, said the S-400 acquisition "could effectively limit India's ability to increase interoperability [with the US]".

When asked if the S-400 purchase could invoke US sanctions under its Countering American Adversaries Through Sanctions Act (CAATSA), Wells said, "There is no blanket waiver or country waiver when it comes to the S-400. We have serious concerns about [India's] possible S-400 purchase, and we are continuing our conversations about how the US or other defence providers could assist India."