President Obama met with Arab leaders of Persian Gulf nations at Camp David in Maryland last May. (AP Photo/Pablo Martinez Monsivais)

President Obama will seek to strengthen a strained relationship with America's long-time ally Saudi Arabia by visiting the kingdom for a summit with Arab leaders of Persian Gulf nations on April 21.

The president will also be traveling to Germany and Britain during the trip, but his visit to Saudi Arabia is likely to draw the most attention. Obama has been a frequent critic of the Saudi monarchy and at times has seemed to question whether a government that helps to spread a harsh and rigid interpretation of Islam should be counted as a true ally of the United States. The Saudis, meanwhile, have quietly expressed unease that Obama has been too accommodating of Iran.

Last spring, Obama invited the Saudis and other Persian Gulf Arab nations to Camp David, where he pledged new American support to help them defend against Iranian missile strikes and cyberattacks.

The meeting, which followed a framework agreement with Iran aimed at preventing it from being able to build a nuclear bomb, was notable in part for the absence of Saudi Arabia's King Salman, who had expressed concern over the negotiations. Only two of the six gulf nations sent their top leaders. In a recent interview with the Atlantic magazine, Obama did little to ease Saudi fears that the United States might be reconsidering its steadfast support for the Saudi monarchy and tilting toward a less combative relationship with Iran.

In the interview, Obama described Iran as a state sponsor of terrorism and a "genuine threat to Israel and many of our allies." He added that "my view has never been that we should throw our traditional allies overboard in favor of Iran.”

But Obama also made it clear that his support for the Saudis in their ongoing proxy war with Iran was far from unwavering. “The competition between the Saudis and the Iranians — which has helped to feed proxy wars and chaos in Syria and Iraq and Yemen — requires us to say to our friends as well as to the Iranians that they need to find an effective way to share the neighborhood and institute some sort of cold peace,” he told the Atlantic. “An approach that said to our friends, ‘You are right, Iran is the source of all problems, and we will support you in dealing with Iran’ would essentially mean that as these sectarian conflicts continue to rage ... we have to start coming in and using our military power to settle scores. And that would be in the interest neither of the United States nor of the Middle East.”

The article also said that Obama has been critical of the Saudis and other gulf monarchies for funneling money to Wahhabi madrassas that have spread a fundamentalist and often anti-American interpretation of Islam to countries such as Indonesia.

“Aren’t the Saudis your friends?” Australian Prime Minister Malcolm Turnbull asked Obama, according to the article.

“It’s complicated,” a smiling Obama replied.

In Saudi Arabia, Obama will participate in a summit with leaders from the Gulf Cooperation Council countries — Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates. The White House said the summit will focus on strengthening cooperation between the United States and its gulf allies, begun at last year's Camp David Summit, and will also provide a forum to discuss the ongoing efforts to destroy the Islamic State and ease tensions with Iran in places such as Yemen and Syria.

In Germany, Obama will take part in the Hannover Messe — the world’s largest trade show for industrial technology — and meet Chancellor Angela Merkel. In Britain, he will be received in London by Queen Elizabeth II at Windsor Palace for a private lunch and will meet with Prime Minister David Cameron.