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Senior American envoys challenged assertions Saturday that Washington seeks to diminish its role in Middle East affairs, insisting that American political ties and energy needs bind U.S. closely to the region.

The defensive tone by U.S. officials in response to questions raised at an international security summit in Bahrain reflects growing speculation about a possible U.S. policy realignment toward Asia at the expense of Mideast initiatives.

Gulf Arab states, in particular, have urged the Obama administration to take stronger action on Syria, where Saudi Arabia and Qatar seek to open channels to send heavy weapons to rebel forces fighting to oust Syrian President Bashar Assad. The White House has favored a more cautious approach with the Syrian opposition, worried that hard-line Islamist rebel factions could be aided by stepped up arms flow.

"The idea that the U.S. can pivot away from the Middle East is the height of foolishness," said Arizona Sen. John McCain at the Bahrain gathering, which brings policymakers and political figures from around the world including Iran and the Syrian opposition.

McCain, the ranking member on the Senate Armed Services Committee, also said he believes there is a "steady increase" in fighters inspired by al-Qaida joining the rebel side in Syria's civil war.

The comments follow a diplomatic flap after Bahrain's crown prince did not mention the U.S. at the opening of the conference Friday as he listed critical allies in the kingdom's 22-month battle against an Arab Spring-inspired uprising. Bahrain is home to the U.S. Navy's 5th Fleet, which is the Pentagon's main counterweight in the region against Iran's military.

Many at the conference interpreted the crown prince's omission as a public slap against Washington for its criticism of Bahrain's crackdowns, including recent action such as banning opposition rallies and revoking citizenship for 31 activists.

More than 55 people have died in the unrest as the island nation's Shiite majority pushes for a greater political voice in the Sunni-ruled kingdom.

The head of the U.S. delegation, Deputy Secretary of State William Burns, credited Bahrain's leadership for some reforms aimed at easing the tensions, including giving more powers to the elected parliament. But he noted "there is much to do" in following through with recommendations by an independent fact-finding committee last year that included calls for investigation into allegations of high-level abuses against protesters.

He also said Middle Eastern oil remains crucial for the world economy despite projections of sharp U.S. crude output in coming years from techniques such as extracting oil from shale.

"While U.S. energy output is growing, in the global economy access to Mideast oil will remain important for the U.S. and other countries," he said.

Burns, however, pointed out that other nations need to help chart the course in the region following the Arab Spring — suggesting no major unilateral push by Washington over Syria or other simmering disputes such as Iran's nuclear program.

"It is important for Americans to understand that the Middle East is not all about us," he told the conference.

Earlier, a senior Saudi official said Gulf Arab states must quash any Arab Spring-inspired unrest or risk threats to their leadership across the oil-rich region.

The comments by Prince Abdulaziz bin Abdullah, the Saudi deputy foreign minister, echoed calls by Gulf authorities to widen crackdowns on perceived opposition such as rights activists and Islamist factions.

His remarks also appeared aimed at justifying the intervention last year in Bahrain by a Saudi-led Gulf military force.

Prince Abdulaziz says Gulf states "cannot tolerate instability" that could lead to challenges to the Western-allied leaders from Kuwait to Oman that have so far ridden out the Arab Spring.

Leaders of the six-nation Gulf Cooperation Council plan to meet later this month in Bahrain with issues such as closer intelligence and security coordination on the agenda.