The entire US power grid could be shut down for more than a month if just nine of the over 55,000 electric substations placed throughout the nation were sabotaged by terrorists or other criminals, according to a new report.

A study by the Federal Energy Regulatory Commission (FERC) found that just a handful of American substations provide much of the electricity that flows to large swaths of the country, sources familiar with the analysis told Rebecca Smith of the Wall Street Journal. Aside from nuclear power plants there are no federal rules requiring utilities to be protected.

This study, though, found that disabling just nine of these substations could leave much of the country without power for weeks, or possibly even months. There are an estimated 30 “crucial” substations that rely on large power transformers to increase the electricity’s voltage, thereby giving it the capability to move long distances.

The Journal report this week is only the first time the results of the study have been made public. Some officials have known about the results for months and have admitted that they would be open to updating security around the plants as well as changing the way electricity is delivered to Americans.

Former FERC chairman Jon Wellinghoff was one of the officials who briefed top US lawmakers on the contents of the report. He recommended that officials propose new security standards for the crucial facilities no later than June.

“There are probably less than 100 critical high voltage substations on our grid in this country that need to be protected from a physical attack,” he told the paper. “It is neither a monumental task, nor is it an inordinate sum of money that would be required to do so.”

The study was inspired by an apparent sniper attack on an electric power station in San Jose, California last April. Snipers opened fire on the power transformers, knocking out 17 and causing millions of dollars in damage. Officials avoided a regional blackout in this case by rerouting the voltage of the path.

No arrests have been made in the case and while the FBI has maintained that there is no evidence the shooting was the product of domestic terrorism, Wellinghoff remains unconvinced.

“This wasn’t an incident where Billy Bob and Joe decided, after a few brewskies, to come in and shoot up a substation,” he said, as quoted by Steve Johnson of the San Jose Mercury News. “This was an event that was well thought out, well planned and they targeted certain components.”

Still, the incident served as a reminder of how few stations are protected by much more than a night time security guard and a chain link fence. In a 2011 incident in Arizona, one transmission line failed, igniting the chain reaction that affected power for millions of people in Arizona and Southern California.

Paul Stockton, a former assistant secretary of defense and president of risk-assessment firm Cloud Peak Analytics, told the Journal that a new solution is overdue.

“The power grid, built over many decades in a benign environment, now faces a range of threats it was never designed to survive,” he said. “That’s got to be the focus going forward.”