America is getting ready for space warfare

The satellites central to national defense and global communications have long faced threats from the ground, such as signal jamming and missile attacks. Orbital menaces are the next frontier.

Intelligence disclosures about Russia’s interest in antisatellite weapons and satellite launches from China have energized U.S. efforts to defend its interests hundreds and even thousands of miles above the Earth’s surface.

Defense companies are developing systems ranging from satellites that can chase other satellites in orbit to protecting ground stations that can beam signals to space. Those protections are critical as mobile navigation services and some television and internet services rely on equipment in orbit. Commercial startups are working on technologies, including orbital capsules, sensors and satellite structures, that could have military applications.

Pentagon officials are also doing something unusual: talking more publicly about the weapons that hostile nations might use in space to engage in warfare. Gen. Chance Saltzman, the Space Force’s top operational leader, said adversaries are trying every day to restrict access that the U.S. and its allies have in space.

“I have got to counter that threat to ensure that the space capabilities that we have come to depend on for our way of life will be there well into the future," he said at an industry conference in March. Military officials, however, won’t discuss details about the U.S.’s own weapon systems in orbit, which are closely held government secrets.

Pointing out Russia’s actions in space has been a particular focus for American officials. Robert Wood, an ambassador for the U.S., recently said at the United Nations that Moscow earlier this month deployed a satellite that likely has attacking capabilities into the same orbit as a U.S. government satellite.

Russia’s U.N. ambassador, Vasily Nebenzya, said in response he didn’t understand what Wood was talking about. The Kremlin has accused the U.S. of seeking to militarize space and called reports that Russia is developing a nuclear antisatellite system fabrications.

Preparing for conflict

The Space Force—the newest military branch—has stepped up training of its Guardians, including how to best maneuver U.S. satellites and predict what adversaries may be planning.

It has developed scenarios for countering lasers, jammers, grabbers and nuclear weapons being used in space. U.S. officials oppose placing its nuclear weapons in orbit, pointing to commitments under a decades-old space treaty, but the Pentagon has been looking to further deploy its own set of space-based arms and capabilities.

In the Space Force’s recent budget request, about 25% of the $29.4 billion funding would go toward so-called space superiority, a concept that Saltzman calls “responsible counter-space."

“We need to act like it’s a war in space," said Robert Winkler at Kratos Defense & Security Solutions, a San Diego-based defense company best known for target drones and is developing a training system for war fighting in space.

It is a two-step process, said military and industry officials. Holding the high ground, be it a hilltop overlooking a battlefield or an orbit thousands of miles above Earth, is a principle that has underpinned military tactics for millennia. Losing those orbital eyes risks blinding missile defenses, a crucial part of nuclear deterrence over the past 65 years.

The second step is transitioning to more mobile assets, just as conflicts on the ground moved from forts and castles to tanks, jets and missiles. Dubbed “dynamic space," these could be maneuvered more easily in orbit, either to stay out of danger or be threatening enough to promote deterrence.

Moving satellites in space requires either energy storage or the ability to replenish fuel or get other services in orbit. Such capabilities are being pursued by a host of commercial companies that are developing potential satellite-moving space tugs, and ones with grabber arms and other robotics.

The recent Space Force commercial strategy calls for harnessing technology and services from private companies to bolster military capabilities during times of crisis. One popular element was a plan to include outside firms in war-gaming to assess the U.S. military’s capabilities, said Even Rogers, chief executive of satellite maker True Anomaly.

His company earlier this year launched two of its Jackal satellites on a SpaceX rocket, looking to test them in an exercise where they would chase each other in orbit. The company didn’t meet all its goals for the flight, which aimed to provide insight into the best ways to maneuver close to other spacecraft. It is making changes for the next flight test.

The arsenal

Pentagon officials frequently describe Russia and China as the main competitors for the U.S. in orbit. They say weapons systems could fall under the “dual-use" category of technology that has military and civilian applications.

China has described its Shijian-21 satellite as having the ability to clean up space debris. But U.S. intelligence and military officials have taken note of an operation carried out more than two years ago, when the satellite was able to move a derelict Chinese navigation satellite.

Russian plans for a space-based nuclear device would threaten the standing the U.S. has carved out in low-Earth orbit, both for a growing commercial sector and military assets. Detonating such a weapon could inflict damage to satellites already deployed and render orbits near Earth as unusable for a year or more, said John Plumb, a recently departed space policy chief at the Pentagon.

The Pentagon’s openness only goes so far. When asked at a recent industry gathering why there was so little talk of U.S. capabilities to go after Russian and Chinese space assets, his answer was brief: “We just don’t."

Write to Doug Cameron at Doug.Cameron@wsj.com and Micah Maidenberg at micah.maidenberg@wsj.com