US President Barack Obama and leaders from six Gulf nations are trying to work through tensions sparked by the US bid for a nuclear deal with Iran, a pursuit that has put regional partners on edge.

Obama is seeking to reassure the Gulf leaders gathering at Camp David that US overtures to Iran will not come at the expense of commitments to their security. He is expected to offer them more military assistance, including increased joint exercises and coordination on ballistic missile systems.

But when Thursday's meetings at the presidential retreat in the Maryland mountains conclude, it's unlikely Obama will have fully assuaged the Gulf's deep-seated fear of Iranian meddling in the region.