India's move to procure military equipment from Russia has not gone down well with the US, which has repeatedly warned Delhi that it might be sanctioned if it goes on with the purchase of S-400s

Subramanian Swamy, a parliamentarian from India's ruling party BJP, has suggested that the United States has been sending "dark hints" to the South Asian nation over New Delhi's purchase of the S-400 missile system from Russia.

In a tweet on Wednesday, Swamy said that though all eyes are on the pandemic, there is a need to watch out for "national threats brewing".
Swamy suggested that the recent incident of a US Navy warship entering India's Exclusive Economic Zone waters without prior permission, as well as US placing India on the currency manipulator list are among those "dark hints" that Washington has been giving out to Delhi.

The BJP leader has also suggested that there's a third hint, too, as he commented on information about the Biden administration sidestepping a question on a US ban on exports of raw materials needed to produce COVID vaccines at the Serum Institute of India.

Swamy has highlighted the trouble brewing in the US-India relationship after Delhi finalised the purchase of S-400s. India signed a $5.5 billion deal for five regiments of the S-400 system in 2018 though the defence system is yet to be delivered.

The defence deal has sparked indignation in the US with the Chair of the US Senate Foreign Relations Committee, Senator Bob Menendez, recently calling India's planned purchase a "matter of concern".

The US has maintained that under the Countering America's Adversaries Through Sanctions Act (CAATSA), India's purchase of the S-400s will "clearly constitute a significant, and therefore sanctionable, transaction with the Russian defence sector".

Despite these threats, New Delhi has so far publicly resisted American pressure.