The leaders from four Persian Gulf states, including Saudi Arabia’s King Salman bin Abdulaziz Al Saudi, are expected to skip President Obama’s meetings with Arab rulers from the Gulf Cooperation Council this week.

Some analysts suggest most of the leaders who were invited are staying away to show their disapproval of the nuclear agreement that the U.S. and five other world powers are trying to reach with Iran.

The leaders of Bahrain, Oman, the United Arab Emirates (UAE), and most notably Saudi Arabia have indicated they will skip the summit, citing various reasons, reports The Associated Press.

Obama was expected to meet with the rulers of the Gulf Cooperation Council countries — Saudi Arabia, Kuwait, the UAE, Qatar, Bahrain and Oman.

“While those nations are still sending representatives to the summit being hosted by President Obama later this week at Camp David, the absence of crucial heads of state — notably, Saudi Arabia’s new king — could present an awkward situation for the administration,” notes Fox News.

Saudi Arabia has been leading an air campaign against Iran-backed Houthi rebels and their allies in Yemen. The Saudi-led Sunni coalition has received logistical support from the U.S.

“We first learned of the King’s possible change of plans from the Saudis on Friday night,” an anonymous senior administration official told various news outlets. “This was confirmed by the Saudis on Saturday. We coordinated closely with our Saudi partners on the alternate arrangement and timing of the announcement, and look forward to welcoming Crown Prince Mohammed bin Nayef and Deputy Crown Prince Mohammed bin Salman.”

Saudi Foreign Minister Adel al-Jubeir, in a statement issued Sunday, said Thursday’s Camp David summit coincides with a humanitarian suspension of hostilities in Yemen.

Although Jubeir confirmed that the king would not be attending the White House meetings, he explained that Crown Prince Mohammed bin Nayef, who also serves as Saudi Arabia’s interior minister, would lead the Saudi delegation, adding that Deputy Crown Prince Mohammed bin Salman,the kings son and the country’s defense minister, will also attend.

On Friday, the White House announced that the Saudi King would attend the summit and would also have a one-on-one meeting with President Obama.

The White House is trying to downplay the change in plans.

“We look forward to the attendance of Crown Prince Mohammed bin Nayef, with whom the President has met on several occasions, including in the Oval Office in December 2014 and January 2013, as well as Deputy Crown Prince Mohammed bin Salman, who the President met when he traveled to Riyadh in January,” a senior administration official told CNN.

The official claimed the White House knew of the King’s change of plans in advance and dismissed the notion that it was because of any substantive disagreement.

“At the summit, leaders of Gulf nations will be looking for assurance that Obama has their support when the region feels under siege from Islamic extremists and Syria, Iraq and Yemen are in various states of chaos,” notes Fox News. “Arab allies also feel threatened by Iran’s rising influence and worry the nuclear pact taking shape with the U.S., Iran and other nations may embolden Tehran to intrude more aggressively in countries of the region.”

A proposal for a common ballistic defense system that could be used as a deterrent to a potentially nuclear armed Iran is also supposed to be discussed at the summit, an unnamed U.S. official confirmed to CNN.

“The official said the goal would be for the Gulf states to operate the missile defense system themselves, with the U.S. providing advisory and technical support,” reports CNN.

“A ballistic missile defense system for the Gulf Cooperation Council is something the Obama administration has recommended for some time, the official noted, and also cautioned that missile defense is only one component of a range of security measures that will be discussed,” it adds.

President Obama disclosed his intention to invite the Gulf allies to a summit the day the framework nuclear agreement with Iran was announced in April as the administration attempts to ease the concerns of those countries over the pact with Iran.

Last Thursday, U.S. Secretary of State John Kerry met with Saudi King Salman to discuss a pause in Yemen’s war and prepare for the Camp David summit.

The Saudi Arabian Foreign Minister the following day announced a five-day truce beginning Tuesday in Yemen so much needed humanitarian aid could be flow into the country.