Twenty-eight years after its Chernobyl nuclear plant exploded, Ukraine confronts a nuclear specter of a different kind: the possibility that the country’s reactors could become military targets in the event of a Russian invasion.

Speaking at the Nuclear Security Summit in The Hague in March, Andrii Deshchytsia, Ukraine’s acting foreign minister, cited the “potential threat to many nuclear facilities” should events deteriorate into open warfare.

Earlier in the month, Ihor Prokopchuk, Ukraine’s ambassador to the International Atomic Energy Agency, circulated a letter to the organization’s board of governors warning that an invasion could bring a “threat of radiation contamination on the territory of Ukraine and the territory of neighboring states.” In Kiev, Ukraine’s parliament responded by calling for international monitors to help protect the plants as the cash-strapped government attempts to boost its own efforts.

Are Ukraine’s concerns mere hyperbole — a “malicious slander,” as the Kremlin puts it — or should we take them seriously? For Ukraine’s government, the angst is real. Even Ukrainians born after 1986 understand what a Chernobyl-type disaster brought about by battle could look like.

History offers little guidance as to whether warring countries would avoid damaging nuclear sites. With the exception of the 1990s Balkan conflict, wars have not been fought against or within countries with nuclear reactors. In the case of the Balkans, Serbian military jets overflew Slovenia’s Krško nuclear power plant in a threatening gesture early in the conflict, while radical Serbian nationalists called for attacks to release the radioactive contents.

Serbia itself later issued a plea to NATO not to bomb its large research reactor in Belgrade. Fortunately, the war ended with both reactors untouched.

While that case provides some assurance that military and political leaders will think twice about attacking nuclear reactors, the sheer scale of Ukraine’s nuclear enterprise calls for far greater global concern. Today, 15 aging plants provide 40 percent of Ukraine’s electricity. (Ukraine shut several reactors operating adjacent to the damaged Chernobyl reactor years ago.) Concentrated in four locations, Ukraine’s pressurized water reactors differ from the less stable Chernobyl RBMK design, yet still remain capable of releasing radioactive contents should safeguards fail.

Given that Russia, too, suffered serious consequences from the Chernobyl accident, it is to be hoped that the Kremlin would recoil at the idea of bombing the plants intentionally. But warfare is rife with accidents and human error, and such an event involving a nuclear plant could cause a meltdown. A loss of off-site power, for example, could be an issue of serious concern. Although nuclear plants are copious producers of electricity, they also require electrical power from other sources to operate. Without incoming energy, cooling pumps will cease functioning and the flow of water that carries heat away from the reactor core — required even when the reactor is in shutdown mode — will stop.

To meet that risk, nuclear plants maintain large emergency diesel generators, which can operate for days — until their fuel runs out. The reactor meltdowns at Japan’s Fukushima No. 1 power station in 2011 demonstrated what happens when primary and emergency operating power are cut.

Such vulnerabilities raise troubling questions in the event of a war. Fighting could disrupt off-site power plants or transmission lines servicing the reactor, and could also prevent diesel fuel from reaching the plant to replenish standby generators. Operators could abandon their posts should violence encroach.

Moreover, combatants could invade nuclear plants and threaten sabotage to release radioactive elements to intimidate their opponents. Others might take refuge there, creating a dangerous standoff. A failure of military command and control or the fog of war could bring plants under bombardment.

Serious radiological contamination could result in each of these scenarios. And, though no one stands to gain from a radioactive release, if war breaks out, we must anticipate the unexpected.

In Ukraine, nuclear emissions could exceed both Chernobyl and Fukushima. Wartime conditions would prevent emergency crews from getting to an affected plant to contain radiological releases should reactor containments fail. And, with government services shut down in the midst of fighting, civilians attempting to escape radioactive contamination would not know what to do or where to go to protect themselves.

Such risks might be one reason for Russian President Vladimir Putin to think twice about ordering a military invasion of Ukraine. But, should war come, combatants must do all they can to keep conflict away from the nuclear sites and the off-site power sources feeding them.

Plant operators should stockpile diesel fuel to keep emergency generators operating. They should perform review and maintenance of generators to ensure that they are set to go. In the event of fighting near reactors, the West should prepare to ferry forces to secure the plants and keep the generators operating; and, in the event of a meltdown, the West should rally both governments to initiate a cease-fire to deal with the disaster. Given the stakes, failure to prepare for the worst is not an option.

Bennett Ramberg is author of “Nuclear Power Plants as Weapons for the Enemy” and “Destruction of Nuclear Energy Facilities in War” © 2014 Project Syndicate