WRIGHT-PATTERSON AIR FORCE BASE -- By year's end, the United States will bring home most if not all its troops from Afghanistan, ending 13 years of war, but future threats will keep the nation's geopolitical and homeland defense radar on alert for decades, experts say.
Just in recent months, Russian troops have invaded the Crimean Peninsula in Ukraine, China has engaged in a territorial standoff with Japan and other neighbors, and U.S. institutions and government agencies have faced a constant barrage of cyber attacks.
But it's the unexpected occurrence that is the most certain outcome in the arena of future threats, said Anthony Cordesman, a military analyst at the Center for Strategic and International Studies in Washington, D.C.
The United States did not predict tensions with Russia over its invasion and annexation of Crimea or China declaring an air defense identification zone in a territorial dispute over the Senkakau/Diaoyu islands also claimed by Japan, the national security expert noted.
"I think it's a warning to the whole idea that you sit there and prioritize," Cordesman said. "The inability to predict the future was about the only thing consistent with predicting the future."
The biggest terrorist attack in the nation's history, the Sept. 11, 2001, attack on America, was not widely anticipated, noted defense analyst John E. Pike, director of GlobalSecurity.org.
"Clearly, a major threat is one that we do not foresee," Pike said.
Defense analysts say some threats can be predicted in the 21st century: the potential of bioterrorism, the specter of nuclear proliferation and the reality of cyber warfare.
"The national economy has been moved online and that makes it much more vulnerable to outsiders than it used to be," said Loren B. Thompson, a defense analyst with the Lexington Institute in Arlington, Va.
"The likelihood of a cyber attack is 100 percent," Thompson said. "In fact, it's happening constantly. The question is how serious it will become. The advanced persistent threats are quite capable of destroying electric distribution or financial institutions if they are not successfully repulsed."
Biotech advances in areas such as gene splicing could mean a greater likelihood terrorists may obtain biological weapons, Thompson said. And he believes the decades-old specter of nuclear weapons still represent the greatest threat to national security.
"Many experts are focused on cyber attacks or biological weapons, but nuclear weapons are the only thing that could destroy America in the next hour," said Thompson.
"The bottom line on nuclear weapons is nobody knows how likely their use is. All we know is there's dozens of them and a few dozen could collapse the U.S. economy."
U.S. adversaries look for vulnerabilities to attack asymmetrically, said Gary O'Connell, National Air and Space Intelligence Center chief scientist at Wright-Patterson Air Force Base.
"Our adversaries or potential adversaries have been watching us for the last 25 years or so and the conflicts we've been involved in, and they've realized they don't want to fight us force on force," he said.
NASIC analysts provide assessments of foreign air, space and cyberspace threats to the president of the United States, congressional leaders and top Pentagon officials, along with other intelligence. Last July, the agency produced a Ballistic & Cruise Missile Threat assessment report with the Defense Intelligence Agency Missile and Space Intelligence Center and the Office of Naval Intelligence. The report examines developments in potential adversaries missile inventories.
NASIC also has on on its radar the fifth-generation fighter aircraft, the Sukhoi PAK FA, a joint Russia and India stealth fighter program, and China's J-20 stealth fighter, according to NASIC commander Col. Aaron Prupas.
"We're looking at what are the advance technologies that are coming down the line in air and space and how will we best be able to create predictive intelligence to make sure that the nation is able to defend against those potential non-permissive or anti-access area of denial environments," he said.
With 3,000 employees at Wright-Patterson, the secretive agency has to determine what threats endanger operations. "We have to be able to say what is going to happen in the future and that is probably some of the biggest challenges in following these technologies," he said.
Efforts to counter U.S. space-based capabilities have gotten a boost, O'Connell said. Adversaries have developed electronic jamming signals to ground-based missiles while pursuing other capabilities, he said.
"Space is becoming more congested, contested and competitive," he said.
Nations have also built up ballistic and cruise missile forces and unmanned aerial vehicles, and are attempting to peer into U.S. cyber, communication and logistic capabilities.
A new Cold War?
Recent security challenges, such as Russia's invasion of Crimea or China's aggressiveness toward Japan and other border nations, may sound like a return to the Cold War.
Conflict with a rising China "inevitably becomes more likely with time as they become more assertive," Pike acknowledged.
Key threats are clearly outlined in the Pentagon's Quadrennial Defense Review, a document released this month that in part lays out future threats to the U.S. and its allies, Cordesman said. The strategic document has three priorities: protect the homeland, build security globally through partnerships and alliances, and project power to win decisively in a conflict.
With smaller budgets than in the post-9/11 era of wars in Afghanistan and Iraq, the Pentagon has re-calibrated strategy, calling for a smaller military to fight and win one regional war and hold off an adversary in another, the document shows.
It calls for replacing or modernizing old weapons systems while reducing the number of personnel and aircraft, ships and other equipment. In the case of the Air Force, the service would send home up to 25,000 airmen -- most of them in the next two years -- and retire hundreds of aircraft.
"You can't afford to have a force posture to deal with every contingency, but you have to have a force posture to deal with the most critical contingencies," Cordesman said.
Top defense leaders have said while they find the risks manageable in the next two fiscal years, deeper cuts under sequestration set to resume in 2016 would threaten the military's ability to carry out is mission and erode the nation's security.
Cordesman doesn't question the nation's defense priorities.
"Whether we are providing the right resources is a different question entirely," he said.
War spending, missing threats?
Paul D. Eaton, a National Security Network senior adviser and a retired Army major general, said the United States has invested heavily to deter strategic threats.
"There do not appear to be from a foreign policy perspective a whole lot of threats to our vital national interests that we can't manage," he said.
America, however, hasn't spent a lot on nuclear non-proliferation, addressing climate change and countering biological weapons, he said.
"Those three are game changers for the United States and basically for mankind," the former two-star general said.
In biotechnology, for example, "the skill set is migrating to an ever lower level and there are guys out there who are tinkering with nature in a way that may not be helpful to mankind," Eaton said. "It's a source of concern, but you don't see a whole lot of activity in the world or in the U.S., in our case, to challenge that."
Some congressional lawmakers are quick to press for military force before allowing diplomacy or economic sanctions to work, he added.
"Instead of allowing the President some space to try to manage Russia's behavior with economic tools and diplomatic tools, we (have) some senators who want to send over F-22s," he said.
Winslow T. Wheeler, director of the Strauss Military Reform Project at the Project On Government Oversight in Washington, D.C., said the threats to the United States are "infinitesimally smaller" than the Cold War when the U.S. faced the Soviet Union and a more hostile communist China.
"To that, the future threat is almost invisible," he said. "If you think it's terrorists, terrorists use a budget probably in the grand total of spending maybe a billion or two per year. We spend more than that (on national defense) in one day."
The money the U.S. has spent to fight terrorism has antagonized populations in countries the United States has fought, he added.
"In fact, what we have done is help the terrorists by making them more widespread," he said.
The United States still spends more on its military than Russia, China, Iran and North Korea combined, Wheeler said.
"We faced a far larger threat during the Cold War," he said. "It was quite real, and now we're spending more and our national security leadership is complaining that the taxpayers are sending them to the poorhouse."