The move comes amid concerns that imposing sanctions, particularly in the case of India and other Asian allies, could threaten friendly relationships that the US has been working to bolster in recent years.

India, the world's top defense importer, has purchased Russian military hardware and expertise for decades, and has been in talks with Moscow to buy S-400 long range surface-to-air missile systems.

Last year, US lawmakers, seeking to punish Russia for its efforts to undermine Western democracy, passed the Counter America's Adversaries Through Sanctions Act, or CAATSA.

"Russia should suffer consequences for its aggressive, destabilizing behavior and its illegal occupation of Ukraine," Mattis said in a statement.

"However, as we impose necessary and well-deserved costs for their malign behavior, providing the Secretary of State with a CAATSA waiver authority is imperative."

Under CAATSA, any entity doing business with Russia's state, semi-state and private defense and intelligence sectors could face economic sanctions.

Appropriate CAATSA waivers allow "nations to build a closer security relationship with the US as they continue to transition from reliance on Russian military equipment," said Mattis, who visited India last year.

India has increasingly turned to the US and France for arms purchases, but is still reliant on Russian hardware and expertise to maintain its existing arsenal.

Mattis said the main question is whether the US wants to strengthen "partners in key regions or leave them with no other option than to turn to Russia."

Amid this week's fallout from President Donald Trump's widely criticized performance at the Helsinki summit with President Vladimir Putin, some Democrats called for a tightening of Russia sanctions.

In August last year, US lawmakers, angered by Russia's alleged meddling in the US presidential election and invasion of Ukraine, passed CAATSA over objections from the White House to oblige a reluctant Trump to cast a wider sanctions net and prevent him from scaling back existing measures.

The State Department did not directly comment on Mattis's suggestion of sanctions waivers.

"This Administration is fully committed to implementing CAATSA," a State Department spokesperson told AFP..

"We have discussed CAATSA with the government of India, and the United States is working with our partners including India to help them identify and avoid engaging in potentially sanctionable activity."