grip challenges confront US security Bruce Riedel, a former CIA officer in the Middle East, tells NBC News' Andrea Mitchell that Iran is capable of making a nuclear weapon but may not have the political will or the money. Al-Qaida remains a threat, but intense U.S.-led pressure is working and could relegate it and similar organizations to having only "symbolic importance," the nation's intelligence chief said Tuesday. When and if that happens, the U.S. will no longer have the luxury of focusing on one dominant threat, James R. Clapper, the director of national intelligence, told senators in the intelligence community's annual assessment of threats to national security. Rather, the "multiplicity and interconnectedness of potential threats, and the actors behind them, "will combine into an amorphous but critical challenge," Clapper said in testimony before the Senate Intelligence Committee. He was joined at the hearing by CIA Director David Petraeus. While people find it easier to identify a single target - like the Soviet Union during the Cold War or al-Qaida during President George W. Bush's war on terrorism - "it is virtually impossible to rank, in terms of long-term importance, the numerous potential threats to U.S. national security," he said. Clapper warned that security challenges today cut across political, economic, military and transnational trends. They reflect a "quickly changing international environment" that includes new political and military developments, the rise of "nonstate actors" - like regional terror and paramilitary groups - and ever-increasing access by individuals to deadly technologies. The good news, he said, is that the resistance to al-Qaida over the past decade has established that sustained pressure works. "The intelligence community sees the next two or three years as a critical transition phase for the terrorist threat, particularly for al-Qaida and like-minded groups," he said. ..." As long as we sustain the pressure on it, we judge that core al-Qaida will be of largely symbolic importance to the global jihadist movement. Take our Facebook poll: Is the U.S. safer today? Clapper, a retired Air Force general and former head of the Defense Intelligence Agency, was confirmed as national intelligence director in August 2010. In his testimony Tuesday, Clapper and Petraeus talked in detail about al-Qaida and other threats to national security: Al-Qaida: The death of Osama bin Laden deprived radical Islam of it "most iconic and inspirational leader" at a time when its capabilities had already been degraded by years of U.S.-led pressure, Clapper said. Al-Qaida's new leader, Ayman al-Zawahiri, is unlikely to change the organization's strategic direction, even though "most al-Qaida members find Zawahiri's leadership style less compelling than bin Laden's image as a holy man and warrior" and "will not offer him the deference they gave bin Laden." As a result, "al-Qaida increasingly will seek to execute smaller, simpler plots to demonstrate relevance to the global jihad," Clapper said. In fact, smaller regional groups like al-Qaida in the Arabian Peninsula and al-Qaida in Iraq are likely to "surpass the remnants of core al-Qaida in Pakistan" as threats to U.S. interests. Syria: It's only a matter of time before Syrian President Bashar Assad falls from power, Clapper said, but it could be a long time because of intervention by Iran and the militant Islamist group Hezbollah and military supplies from North Korea. That makes it difficult for the West to plan for "a post-Assad situation," he said. Weapons of mass destruction: The spread of biological, chemical and nuclear weapons is "among our top concerns," Clapper said, because "the time when only a few states had access to the most dangerous technologies is past." Biological and chemical materials "move easily in our globalized economy, as do the personnel with scientific expertise to design and use them," he said. Open Channel: Israeli Embassy, US tourists among likely targets of bomb plot While no recognized countries are yet known to have provided direct WMD assistance to terrorist groups, that could change: "As governments become unstable and transform, WMD-related materials may become vulnerable to nonstate actors, if the security that protects them erodes," he said. Iran: Petraeus said he believed the International Atomic Energy Agency's report in November - which said Iran is on the verge of a nuclear "breakthrough" that could allow it to launch a missile able to hit Israel and Europe - is accurate. But Iran's willingness to allow IAEA inspectors to extend their stay in Tehran this week indicates that new sanctions on Iran's central bank are beginning to bite. NBC News has reported that China, Iran's biggest oil customer, has recently reduced its purchases of Iranian oil after behind-the-scenes negotiations with U.S. Msnbc.com: Will Iran make good on its threat against US? North Korea: The death of supreme leader Kim Jong-il is unlikely to lead to any fundamental change in Pyongyang's isolation and belligerence, Petraeus said. There's no reason to believe, he warned that the new leader, Kim Jong-un, will stop the country's exports of ballistic missiles and other materials to Iran, Syria and possibly other countries. Cyber-threats: Advances in information technology have opened the door to mass-scale collection of personal and governmental data by China, Russia and numerous independent groups, Clapper said. Unfortunately, "innovation in functionality is outpacing innovation in security, and neither the public nor private sector has been successful at fully implementing existing best practices," he said. That's shown by well-publicized intrusions into the NASDAQ computer system and International Monetary Fund networks, underscoring the "vulnerability" of the U.S. economy. Health threats and natural disasters: Clapper pointed to the earthquake and tsunami in Japan as an example of what could go wrong even when a government acts appropriately. "Although Tokyo responded adequately in the immediate aftermath of Japan's largest earthquake, the triple disaster contributed to Prime Minister (Naoto) Kan's resignation," he said. Beyond the immediate health and safety concerns, such developments open the way for militant groups to "challenge and potentially destabilize governments" that never would have been considered vulnerable, he said. "Although we can say with near certainty that new outbreaks of disease and catastrophic natural disasters will occur during the next several years, we cannot predict their timing, locations, causes or severity," he warned. Andrea Mitchell and Courtney Kube of NBC News contributed to this report from Washington.