WASHINGTON — The Pentagon is asking all military personnel, civilian officials and contractors to report any anomalous health episodes similar to the illnesses that have befallen diplomats and C.I.A. officers at the American Embassy in Havana, according to a new departmentwide message.

The message, signed by Defense Secretary Lloyd J. Austin III, is an effort to step up reporting from around the globe, and in the United States, to get treatment to those who need it and to help counterintelligence investigators gather more information about the rash of episodes that have injured at least 200 Americans.

The memo, along with other documents provided to military counterintelligence officials, lays out suspected signs of the attacks from accounts of the injured, including heat, pressure and noise. It also details symptoms associated with the so-called Havana syndrome such as nausea, headaches, pain and vertigo.

Crucially, defense officials emphasized, the memo, which was sent to 2.9 million military service members and Defense Department civilians, outlines how to respond: Quickly move away from the area.

“Timely reporting is essential and starts with knowing what to do if you experience A.H.I.,” Mr. Austin wrote, using the abbreviation for anomalous health incident.

Military personnel must then report the episode to the chain of command, security officers and medical providers, Mr. Austin wrote.

The memo is part of a governmentwide effort to collect more information about the episodes and comes as intelligence officials continue to struggle to make clear attribution on who is responsible. Intelligence agencies are getting closer to making some conclusions, but the government is not close enough to make an “analytic judgment,” David S. Cohen, the deputy C.I.A. director, said this week.

“There’s a classic intelligence problem, and we are approaching it with the same techniques,” Mr. Cohen said at the annual Intelligence and National Security Summit. “This is a serious issue. It’s real, it’s affecting our officers, it’s affecting others around their community and in government.”

“We’re going to figure it out,” he added.

There are various reasons the United States has struggled to identify who, and what, is responsible for the episodes. Officials have considered that intelligence services from multiple countries could be involved, each with varying motives and equipment causing the illnesses, according to some U.S. officials.

Officials stress that the possibility of multiple adversaries remains only a theory, and that intelligence officials have yet to draw hard conclusions.

But Cold War-era surveillance technology developed by the Soviet Union proliferated to other countries, each of which has equipment that could prompt symptoms similar to previous attacks.

In at least some of the Havana syndrome cases, the technology was used by the G.R.U., Russia’s military intelligence agency, to eavesdrop but not to deliberately injure, according to some American officials. But other later episodes look more like deliberate attacks by the G.R.U., these officials said.

In other cases Russian intelligence may not be involved at all, beyond having shared the technology. Some intelligence agencies may have used faulty or badly calibrated microwave-based surveillance technology and inadvertently injured the American officials they were spying on.

The first batch of cases occurred at the American Embassy in Havana in 2016 and 2017. The next group occurred at diplomatic outposts in China, a country where it would have been difficult for Russian intelligence to operate, according to officials briefed on the intelligence.

Since then, officials have tracked cases in Europe and Asia.

Representative Adam B. Schiff, Democrat of California and the chairman of the House Intelligence Committee, said in an interview this summer that multiple countries could be involved and that it was critical not to dismiss various explanations.

“I don’t think we can exclude any possibility here, that there are multiple causes of these injuries and that there are multiple players involved in these injuries,” Mr. Schiff said. “I think any of that is feasible.”

The House is considering a Senate-approved bill that would expand assistance to current and former government officials injured in anomalous incidents and suffering from the Havana syndrome. A vote scheduled in July was delayed by partisan fighting, but some officials say another chance to vote could come by the end of the month.

In July, William J. Burns, the C.I.A. director, told NPR that there were roughly 200 Havana syndrome cases, half of which involved agency personnel. Since then, additional episodes have occurred, including one in Vietnam that temporarily delayed Vice President Kamala Harris’s visit to the country. Other cases have been removed from study, with officials believing they do not fit the syndrome’s pattern.

Additional reports can help investigators learn more about the attacks, detect patterns and get closer to determining a cause, a senior defense official said.

The Pentagon memo to the work force was delayed for months as officials installed procedures to better investigate episodes and smooth the path to medical care for the injured.

While the most serious cases among military officials will be treated at Walter Reed National Military Medical Center, less grave cases could be treated locally.

In the memo, Mr. Austin urged service members and others to report any episodes, particularly ones that have similarities to the Havana syndrome affecting diplomats and C.I.A. officers stationed in Cuba.

Mr. Austin’s memo said the episodes had occurred “predominantly overseas.” But Pentagon officials and documents have acknowledged that while that is the case, some of the anomalies have occurred in the United States.

Administration officials have previously said that two episodes in the Washington, D.C., area could be possible examples of Havana syndrome.

Throughout the year, White House and other government officials have tried to raise awareness of the episodes and encourage people to report symptoms of the syndrome but also avoid creating panic.

The new Pentagon advice is based on the experience of military personnel who have been injured and have symptoms of Havana syndrome.

That includes one case, in the fall of 2020, when a military officer serving overseas pulled his vehicle into an intersection, then was overcome by nausea and headaches. His 2-year-old son, sitting in the back seat, began crying. When the officer quickly pulled away from the intersection, his nausea stopped and the child stopped crying, a chain of events that helped solidify the military advice that troops move out of the contact area as quickly as possible.