Amid murky nuclear talks between the United States and Iran, a group of Republican senators has drawn a line in the sand on enrichment.

Sens. Katie Britt (R., Ala.), Tom Cotton (R., Ark.), and Lindsey Graham (R., S.C.) last week introduced a resolution demanding the "complete dismantlement and destruction of Iran’s nuclear program" in any agreement struck between Washington and Tehran—a condition President Donald Trump may not attach to a new deal.

The resolution holds that any pact between the two countries must mandate that Iran "forgo domestic uranium enrichment, the reprocessing of spent fuel, and the development or possession of any enrichment or reprocessing infrastructure or capacity."

Despite the clear language from Republican senators, the executive branch has sent mixed messages on whether it will allow Iran to continue enriching uranium as part of a revamped nuclear deal—perhaps the most contentious aspect of any agreement.