Gulf Arab countries and the United States have agreed to deploy joint patrols to intercept ships smuggling Iranian weapons to Yemen.
The secretary-general of the Gulf Cooperation Council (GCC) said the bloc and the US would stage joint maritime patrols to stop weapons smuggling from Iran.
Tuesday's agreement was reached during a meeting between US Defense Secretary Ash Carter and his Gulf Arab counterparts in Riyadh.
The two sides also agreed on joint cooperation towards improving Gulf missile defence, special forces and maritime security, but no new deals were announced.
OPINION - Saudi Arabia, Iran and the 'Great Game' in Yemen
Carter is part of the US delegation accompanying President Barack Obama on his current visit to Saudi Arabia.
National Security Adviser Susan Rice and CIA Director John Brennan are among Obama's entourage, demonstrating the focus on security in the president's agenda with his Gulf counterparts.
Also on Wednesday, Obama met Saudi Arabia's King Salman. There was no information on what the two leaders discussed in the two-hour meeting.
On Thursday, Obama will attend a GCC summit that comprises Saudi Arabia, Kuwait, Qatar, Bahrain, the United Arab Emirates and Oman.
OPINION - The Obama Doctrine: Middle East out, Asia in
Most of the Gulf Arab monarchies have in private been sorely disappointed by Obama's presidency, regarding it as a period in which the US has pulled back from the region, giving more space to their archrival Iran to expand its influence.
For his part, Obama has spoken of his desire to persuade Gulf states to arrive at a "cold peace" with Iran that would douse sectarian tensions and allow all sides to focus on what he sees as a greater threat emanating from the Islamic State of Iraq and the Levant (ISIL).