The think tank added that Russia's share of Indian oil imports fell from 51 per cent in July to 44 per cent in August as India bought more from the US US President Donald Trump's waiver from sanctions, restrictions and tariffs under the Sanctioning Russia and Iran Act (SRIA) gives India temporary relief but offers no lasting certainty, and New Delhi should safeguard its energy security and buy oil on commercial terms, think tank GTRI said on Saturday.