Airmen work in the Joint Space Operations Center at Vandenberg Air Force Base in California. The center detects, tracks, and identifies all artificial objects in Earth orbit. (U.S. Air Force/U.S. Air Force)

The first salvo was a missile launch by the Chinese in 2007 that blew up a dead satellite and littered space with thousands of pieces of debris. But it was another Chinese launch three years ago that made the Pentagon really snap to attention, opening up the possibility that outer space would become a new front in modern warfare.

This time, the rocket reached close to a far more distant orbit — one that’s more than 22,000 miles away — and just happens to be where the United States parks its most sensitive national security satellites, used for tasks such as guiding precision bombs and spying on adversaries.

The flyby served as a wake-up call and prompted the Defense Department and intelligence agencies to begin spending billions of dollars to protect what Air Force Gen. John Hyten in an interview called the “most valuable real estate in space.”

Faced with the prospect of hostilities there, defense officials are developing ways to protect exposed satellites floating in orbit and to keep apprised of what an enemy is doing hundreds, if not thousands, of miles above Earth’s surface. They are making satellites more resilient, enabling them to withstand jamming efforts.

And instead of relying only on large and expensive systems, defense officials plan to send swarms of small satellites into orbit that are much more difficult to target.

GPS III is the next generation of GPS satellites that will introduce new capabilities to meet the higher demands of both military and civilian users. In this photo, two contractors work on a GPS III satellite. (U.S. Air Force)

At the same time, the Pentagon has designated the Air Force secretary a “principal space adviser,” with authority to coordinate actions in space across the Defense Department. Agencies have begun participating in war-game scenarios involving space combat at the recently activated Joint Interagency Combined Space Operations Center.

The flurry of activity raises the specter of a new technological arms race, this one in space, as nations jockey for advantage. The Pentagon is even developing what is known as the “Space Fence,” which would allow it to better track debris in space.

National security officials are not only concerned that missiles could take out their satellites but also that a craft’s equipment could be easily jammed. Potential enemies could “dazzle” sensors, temporarily blinding them, or deploy tiny “parasitic satellites” that attach to host satellites and do their worst. That could lead to soldiers stranded on the battlefield with little means of communication or missiles that would not be able to find their targets.

“We have considered space a sanctuary for quite some time. And therefore a lot of our systems are big, expensive, enormously capable, but enormously vulnerable,” said Deputy Defense Secretary Robert O. Work.

Perhaps most striking is how openly Pentagon officials are talking about their efforts to fight in space — especially because much of the work remains highly classified.

While the United States has been bogged down in counter­terrorism operations in Iraq and Afghanistan, Pentagon officials say that Russia and China have been developing the capability to attack the United States in space.

“Every military operation that takes place in the world today is critically dependent on space in one way or another,” said Hyten, commander of the Air Force Space Command. “Whether our own people in the United States are fully cognizant of the dependence on space or not, the rest of the world has been watching us very closely.”

Russia launched its inaugural rocket from a new cosmodrome on April 28, a day after a technical glitch thwarted the much-publicized event. An unmanned Soyuz-2.1 rocket carrying three satellites soared off into orbit successfully from the launch pad in the remote Amur region. (Reuters)

Since the 1991 Persian Gulf War, the United States has become increasingly reliant on space for how it fights. Its satellites are used to snap images of the enemy, provide communications in remote areas, and guide ships, drones and even bombs via GPS. That same navigation technology also has become embedded into everyday life for Americans, who rely on satellites for driving directions, television signals and more. Even the banking system uses GPS to time transactions.

Those high-tech capabilities have given the U.S. military an extraordinary advantage over its adversaries, and over the years, the military has launched dozens of satellites into space.

Now, as Russia, China and others develop technology that could take out the national security infrastructure the United States has built in space, Pentagon officials fear its satellites could be sitting ducks. Navy Adm. Cecil Haney, commander of the U.S. Strategic Command, said recently that North Korea has successfully jammed GPS satellites, that Iran was busy building a space program and that “violent extremist organizations” were able to access space-based technologies to help them encrypt communications, among other things.

“We must recognize that despite our efforts, a future conflict may start, or extend, into space,” he said.

Although Hyten and others had long been concerned about the mounting arms race in space, it was only after the 2013 launch by the Chinese that the Pentagon acted with a new sense of urgency.

As adversaries began targeting space, “there was a level of frustration ” in the space community, Hyten said. “We just needed someone to say go.”

The “go” came in 2014, when top Pentagon officials, including Work, the deputy defense secretary, made space a priority, saying at a meeting that “if, God forbid, someday a conflict does extend from the Earth to space, what are you going to do about it?” Hyten recalled.

The Pentagon spends $22 billion on space programs and is investing an additional $5 billion in space efforts this year, including $2 billion for what is known as “space control,” which includes its highly classified offensive programs. Hyten declined to discuss the ways in which the United States is preparing to attack other countries in space. But the United States has had the capability to blow up satellites since 1985, when an F-15 fighter pilot fired a missile into space that took out an old military observation satellite.

The Pentagon is moving in the right direction, said Elbridge Colby, a senior fellow at the Center for a New American Security, because if the United States was to get into a conflict with Russia or China, “we should count on them going into space because it’s so important to us, and it’s quite vulnerable.”

The new space operations center has been up and running for just more than six months. It had what Hyten called “a very slow start because we just hadn’t thought about it.” But officials have begun running through scenarios and identifying weaknesses in defense, which help officials tear down the walls between different fiefdoms, he said, so communication and planning can improve.

Most of all, there has been a culture change, he said. Where Pentagon officials who focused on space once operated in what was a peaceful environment, they have had to think of themselves — and space — differently.

“They are warriors,” Hyten said. “And they need to recognize that they are war fighters.”

Not that the Pentagon is inviting war. Its preparations are to deter conflicts, not incite them, officials said.

During a recent speech, Frank Rose, the assistant secretary of state for arms control, verification and compliance, said he was “concerned about the continued development by Russia and China of anti­satellite weapons.” But he said the United States “is committed to preventing conflict from extending into space, and our diplomatic strategy supports this goal. The possibility of conflict in space is in no one’s interest.”

Part of that is speaking out publicly about a highly sensitive subject.

“The fact that the Pentagon is being so vocal, consistent and in some sense you could say dramatic is an indication of how serious the problem is,” Colby said.

When China flew its missile to near what’s known as geo­stationary orbit — the orbit where the Pentagon has many of its satellites — that “appears to have scared the crap out of people,” said Brian Weeden, a technical adviser for Secure World Foundation.

At the time, Chinese officials said they had tested a land-based missile interceptor and denied that the weapon was designed to destroy satellites.

Russia also got the Pentagon’s attention when one of its satellites, launched in 2014, flew between two commercial Intelsat communications satellites and then sidled up to a third.

“It did not pose a collision risk, but it was uncomfortably close,” Weeden said.

The Russian Embassy in Washington did not respond to a request for comment.

Without space, the United States would be forced to revert to “industrial age warfare,” Hyten said.

“It’s Vietnam, Korea and World War II,” he said. No more precision missiles and smart bombs. “Which means casualties are higher, collateral damage is higher. . . . We don’t want to fight that way because that’s not the American way of war today.”