U.S. President Barack Obama pledged America's "ironclad commitment" to anxious Persian Gulf nations Thursday, May 14, to help protect their security, pointedly mentioning the potential use of military force and offering assurances that a potential nuclear agreement with Iran would not leave them more vulnerable, the Associated Press reports.

Obama said the U.S. would join the Gulf Cooperation Council nations "to deter and confront an external threat to any GCC state's territorial integrity." The U.S. pledged to bolster its security cooperation with the Gulf on counterterrorism, maritime security, cybersecurity and ballistic missile defense.

"Let me underscore, the United States keeps our commitments," Obama said at a news conference.

Thursday's meeting at Obama's retreat in the Maryland mountains was aimed at quelling the Gulf's fears of U.S.-led nuclear talks with Iran. Gulf states worry that if Iran wins international sanctions relief, the influx of cash would embolden what they see as Tehran's aggression in the region, the AP says.

The president acknowledged those concerns, but said the U.S. believes Iran's focus would be on shoring up an economy that has struggled under the sanctions pressure.

Obama and top advisers walked the Gulf nations through the work-in-progress nuclear deal in detail during private meetings Thursday. The president said that while the Gulf leaders hadn't been asked to "sign on the bottom line" to approve the framework, they did agree "that a comprehensive, verifiable solution that fully addresses the regional and international concerns about Iran's nuclear program is in the security interests of the international community, including our GCC partners."

Saudi Foreign Minister Adel al-Jubeir said Arab leaders were "assured that the objective is to deny Iran the ability to obtain a nuclear weapon" and that all pathways to such a weapon would be cut off. He added that it was too early to know if a final nuclear agreement would be acceptable, saying, "We don't know if the Iranians will accept the terms they need to accept."

The U.S. and five other nations are working to finalize the nuclear deal ahead of an end of June deadline.

As if to underscore Gulf concerns, an Iranian naval patrol boat fired on a Singapore-flagged commercial ship in the Persian Gulf Thursday. A U.S. official said it was an apparent attempt to disable the ship over a financial dispute involving damage to an Iranian oil platform.

The incident took place a bit south of the island of Abu Musa just inside the Gulf, according to the U.S. official, who was not authorized to discuss details by name. The White House said no Americans were involved in the incident.

Thursday's summit marked an unusual investment by Obama in his relationship with the Gulf. He rarely uses Camp David for personal or official business, but White House aides hoped the more intimate setting would lead to a more candid conversation with the Arab allies, the AP says.