In the Soviet playbook for all-out war with the United States, the wasting of U.S. cities by nuclear bombs was to be followed by something equally horrifying: waves of plagues to kill any survivors. Soviet scientists spent decades preparing for the second attack, concocting new kinds of biological weapons more lethal than any ever invented.

None of these weapons were used during the Cold War, but a new book suggests that the dangers posed by the program never completely abated. The authors reveal new details about the deadly achievements of Soviet weapons scientists — from multiple-drug-resistant anthrax to “stealth” bugs that elude detection — and they say the strains probably still exist inside the freezers of military laboratories inside Russia.

The book also suggests that U.S. intelligence operatives may have inadvertently fueled the Soviets’ experimentation with germ warfare, in part by spreading false stories that convinced communist leaders that the United States was also secretly making such weapons after the U.S. program was officially halted in 1969.

At minimum, Soviet officials appear to have increased production of an anthrax weapon because they falsely believed that the United States was doing the same, contend the authors of “The Soviet Biological Weapons Program,” an exhaustively researched, 890-page history of the Soviet Union’s 65-year effort to develop the tools for germ warfare.

“It may have led to the massive expansion of the Soviet b. anthracis program,” write Milton Leitenberg and Raymond Zilinskas, scientists and biological weapons experts who interviewed some of the Soviet Union’s former top bioweaponeers during more than a decade of research for the book.

Russia maintains a policy of official denial with regard to Soviet-era production of bioweapons, which were banned by an international treaty signed by the Soviet Union in 1972. But former Russian president Boris Yeltsin confirmed the existence of a secret Soviet program to top U.S. officials in the early 1990s, and since then, defectors, former Soviet scientists, U.S. officials and journalists have published extensive accounts.

Such reports revealed the outlines of a vast program that employed tens of thousands of people at its peak, and they also shed light on the 1979 industrial accident in a bioweapons plant in the Soviet city of Sverdlovsk, in which anthrax spores spread through a residential area, killing at least 68 people.

Leitenberg and Zilinskas draw from hundreds of interviews, documents and intelligence files to generate a catalogue of the Soviet bioweapons arsenal and its intended use. Among their book’s revelations is an account of a largely successful Soviet effort to engineer deadly new strains, such as drug-resistant forms of the bacteria that cause anthrax and tularemia.

In one of their more chilling accomplishments, Soviet scientists learned to alter microbes to give them stealthy characteristics, the authors say. The bacteria that cause plague, for instance — Yersina pestis — were modified so that standard medical tests could not detect an infection until the disease had progressed to an advanced stage, the authors say.

Similar changes were made to a strain of the bacteria that cause Legionnaire’s disease. In the altered state, the bacteria would stimulate the body’s immune response to conceal symptoms of the disease, while simultaneously secreting a toxin that attacks a critical component of the nervous system known as myelin.

“The destruction of myelin . . . induces an illness similar to multiple sclerosis, but with a quick death,” the authors state.

Despite such achievements, the Soviet program suffered from deficiencies and gaps, including a failure to perfect delivery vehicles such as missile warheads.

The gaps suggest that Soviet leaders were conflicted over how and when to use such weapons. One theory, explored by the authors, is that biological weapons were “developed not for military purposes, but for sabotage or terrorism.”

Details about the dismantling of the bioweapons program after the Soviet Union’s collapse have been kept secret for two decades. Despite repeated requests, Russian officials also have refused to allow outside access to three biological laboratories operated by the Defense Ministry.

The labs were part of the Soviet-era program, and it is “reasonable to conclude” that collections of microbes from the weapons program are warehoused there, in the same way that disease strains are kept in heavily guarded military and civilian laboratories in the United States, the authors say. They add that the lack of any transparency raises concerns about the security of the collections and the possibility of continuing research.

“One must assume that whatever genetically engineered bacterial and viral forms were created . . . remain stored in the culture collections of the Russian Federation Ministry of Defense,” the authors write.