WASHINGTON — The United States faces an evolving list of potential adversaries in the 21st century that not only continue to seek weapons of mass destruction, but are honing the skills necessary to wage battle in cyberspace as well as outer space, a panel of national security experts said Jan. 20.

The nature of warfare has changed significantly since the end of the 20th century, with new technologies and threats emerging faster than ever, U.S. Air Force Gen. Robert Kehler, commander of Air Force Space Command, said during a panel discussion at the Conference on National Security Strategy and Policy here. The conference was sponsored by the Institute for Foreign Policy Analysis and Tufts University’s Fletcher School of Law and Diplomacy.

“If you think about what has happened over the last century with air power changing our conception of time and distance, I believe that that advent of the military use of real-time space power has changed our views of time and distance again,” Kehler said. “And I think cyberspace will do that again.”

In addition to its responsibility to field and maintain space capabilities for the Air Force, Air Force Space Command recently took on the service’s responsibility for the cyber domain, while responsibility for the nation’s ICBM fleet was transferred to Air Force Global Strike Command. The 24th Air Force was established last year at Lackland Air Force Base, Texas, to handle the new cyber mission, and Kehler certified its initial operational capability on Jan. 22.

The notion of national and regional boundaries has changed in recent years with the use of cyber- and space-based technologies, Kehler said. Adversaries today intentionally use the U.S. military’s geographic partitions to their advantage, and the time may be right to think about organizing the military differently to address this.

“There are days when I wonder if a global perspective rather than a theater perspective is being adequately addressed,” Kehler said. “Boundaries drawn today may not have any application in space and cyberspace.”

The global security landscape in the 21st century is also likely to be marked by the pursuit of weapons of mass destruction by both nation states and non-nation states, said Robert G. Joseph, senior scholar at the National Institute for Public Policy and former U.S. undersecretary of state for arms control and international security. In addition to the eight nations that acknowledge having a nuclear weapons program today, Iran and North Korea continue to aggressively pursue nuclear programs, Joseph said.

“It’s fair to say that the trend is not positive,” Joseph said. “In addition, there are other states hostile to the United States that may seek to acquire nuclear weapons: Syria, Burma and Venezuela come to mind. Then there are states allied with us that may decide for any number of reasons to go nuclear: Japan, Taiwan, Egypt, Turkey, Saudi Arabia.”

The biggest wildcard is China, which continues its military buildup across the board, including the modernization of its nuclear forces, Joseph said.

“China is unique among the [Nuclear Non-Proliferation Treaty]-recognized states,” he said. “While all the others are reducing their nuclear postures, China is moving in the opposite direction. This includes the development of next-generation tactical and strategic systems. By 2015, China is projected to have in excess of 100 nuclear-armed missiles.

“China’s search for asymmetrical advantages also places great emphasis on perceived U.S. vulnerabilities in space and cyberspace. Notably there are indications that China has been developing the capability for electromagnetic pulse warfare.”

Kehler noted that while much attention has been paid to China’s 2007 test of a kinetic anti-satellite weapon, it may have been an attempt to distract the United States from more pressing Chinese threats in the cyber domain.

“For those of us who have children, remember when you would take the kids to the doctor for shots when they were little? The doctor would always have a blue bear that they would hold up, and the kid would look up and then they’d give the shot. I’m not so sure the direct ascent A-sat isn’t the blue bear,” Kehler said.

In addition to nuclear proliferation, this century is likely to see more weak states, armed groups and irregular warfare, said Richard Shultz, director of the Fletcher School’s international security studies program.

Shultz cited Iraq in 2003 as an example of a weak state. With the removal of Saddam Hussein’s regime, the United States was not prepared to deal with the sectarian violence that emerged and it took several years to stabilize the country, he said.

Today, Mexico is a nation the United States will have to pay close attention to, as it has all the earmarks of a weak state, Shultz said. The government does not fully control its territory, parts of its territory are ungoverned and armed groups have been able to assert their influence across Mexico and terrorize state and local officials with impunity, he said.

“We will not be able to fight the war that we would like to fight,” Shultz said. “Rather, increasingly we will have to deal with enemies who will challenge us asymmetrically in ways that we are least prepared to deal with.”