U.S. Secretary of Defense Chuck Hagel, left, greets Saudi Arabia Deputy Minister of Defense Prince Salman bin Sultan, before a meeting at the Radisson Hotel, on Friday, Dec. 6, 2013 in Manama, Bahrain. Secretary Hagel is visiting Bahrain while on a six day trip to the middle east, and is scheduled to speak at the Manama Dialogue Regional Security Summit tomorrow. Saudi Arabia Deputy Minister of Defense Prince Salman bin Sultan, left, arrives for a meeting with Secretary of Defense Chuck Hagel at the Radisson Hotel, on Friday, Dec. 6, 2013 in Manama, Bahrain. U.S. Secretary of Defense Chuck Hagel, left, meets with King Hamad bin Isa Al Khalifa of Bahrain on Friday, Dec. 6, 2013 at the Safriya Palace, Sadad, Bahrain, southwest of the capital of Manama. Secretary Hagel is visiting Bahrain during a six day trip to the middle east. King Hamad bin Isa Al Khalifa of Bahrain meets with U.S. Secretary of Defense Chuck Hagel on Friday, Dec. 6, 2013 at the Safriya Palace, Sadad, Bahrain, southwest of the capital of Manama. Men carry tea to serve to U.S. Secretary of Defense Chuck Hagel and King Hamad bin Isa Al Khalifa of Bahrain during their meeting on Friday, Dec. 6, 2013 at the Safriya Palace, Sadad, Bahrain, southwest of the capital of Manama. MANAMA, Bahrain (AP) - U.S. Defense Secretary Chuck Hagel opened the door for the U.S. to sell missile defense and other weapons systems to U.S.-friendly Gulf nations, with an eye toward boosting their abilities to counter Iran's ballistic missiles, even as global powers ink a nuclear deal with Tehran. In a speech Saturday to Gulf leaders, Hagel made it clear that the emerging global agreement that would limit Iran's nuclear program doesn't mean the security threat from Iran is over. Instead, he laid out steps to beef up defense cooperation in the Gulf region, while at the same time insisting that America's military commitment to the Middle East will continue. "I am under no illusions, like all of you, about the daily threats facing this region, or the current anxieties that I know exist here in the Gulf," Hagel told a security conference. These anxieties have emerged as the United States pursues diplomatic openings on some of the region's most difficult problems and most complex issues, including Iran's nuclear program and the conflict in Syria. He said the interim deal is just a first step that has bought time for meaningful negotiations, adding that "all of us are clear-eyed, very clear-eyed about the challenges that remain" to reaching a nuclear solution with Iran. And he pointed to the ongoing plan to destroy Syria's chemical weapons as diplomacy made possible by America's military threat. He said President Barack Obama's threat to strike Syria after a chemical weapons attack believed to be the work of Bashar Assad's government led to the ultimate deal to remove and destroy the arsenal. But Hagel argued that the emphasis on diplomacy must not be misinterpreted. "We know diplomacy cannot operate in a vacuum," Hagel said. Our success will continue to hinge on America's military power, and the credibility of our assurances to our allies and partners in the Middle East that we will use it. And, he warned that with America's sophisticated weapons, "no target is beyond our reach." As part of the security effort, he said the U.S. wants to take steps to beef up the Gulf region's ability to defense itself. Hagel's speech continued a theme he has repeated over the past two days in private meetings with Gulf leaders and in remarks to troops aboard the Navy's USS Ponce warship at the nearby U.S. base. Hagel was challenged at one point during a question-and-answer session by a former Iranian nuclear negotiator over why his address failed to mention Israel's possession of nuclear weapons. Hossein Mousavian, who is now a scholar at Princeton's Woodrow Wilson School of Public and International Affairs, told Hagel he "didn't mention a single word about the major threat of nuclear bombs in the region, which is Israel." Hagel replied by noting that Iran is in violation of "many United Nations resolutions." Israel is widely understood to possess nuclear weapons but declines to confirm it. Hagel spent a chunk of the speech detailing the strength of the U.S. military in the area, including more than 35,000 air, land and sea forces in and immediately around the Gulf. The most concrete proposal Hagel outlined is the Pentagon's plan to allow military sales to the Gulf Cooperation Council, so the six-member nations can have more coordinated radars, sensors and early warning missile defense systems. Hagel is expected to visit Qatar and Saudi Arabia to meet with leaders in the coming days. Associated Press writer Adam Schreck contributed to this report.