As Moscow braces to host the third round of talks on Iranian nuclear program the US Senators are urging President Obama to ramp up pressure against Tehran and show that “credible military option” exists should Iran fail to curb its nuclear program.

Forty-four senators, both Republicans and Democrats, have addressed Barack Obama in a letter stating that Iran must immediately take steps to shut down the Fordow facility, freeze the enrichment of uranium above 5 per cent and ship uranium already enriched above 5 per cent out of the country.