Trump said last week that his administration would not sell F-35 stealth fighters to Turkey but stopped short of announcing sanctions under a 2017 law that penalizes dealings with the Russian military.
But Congress has taken a tougher stance, piling pressure on Trump to impose curbs on Turkey ranging from entry bans to denial of export licenses, according to The Wall Street Journal.
If Trump waives sanctions or imposes symbolic restrictions, lawmakers may opt for congressional action against Turkey or its military unit that was responsible for the S-400 acquisition, the newspaper said.
In 2017 Turkey signed a $2.5 billion deal with Russia to purchase its S-400 surface-to-air missiles. The next year, the US offered Turkey to buy its Patriot missile systems but Ankara has not accepted the deal yet, adding that Russia's terms for its defence systems were better. Washington has repeatedly urged Ankara to abandon the S-400 deal with Russia, claiming that they are incompatible with NATO defences.
Washington also says that having the S-400 systems Turkey could compromise the F-35 stealth jet project it had previously joined. Ankara, for its part, insisted that its deal with Russia would not be reconsidered but also added that it had no plans to quit the F-35 programme.