With last year’s major terrorist attacks in Paris and California, most Americans are increasingly worried about the ability of ISIS- directed or ISIS-inspired attacks. Global terror attacks have become a major topic in the 2016 presidential campaign.

But other national security fears are on the mind of former U.S. Defense Secretary William J. Perry. While last year’s terrorist attacks killed dozens of people, Perry’s nightmares, centered around terrorists using nuclear material or an escalation-to-war between nuclear-equipped nations, could kills tens of thousands or more.

While some presidential candidates for the 2016 election talk tough and dish provocative sound bites, Perry speaks rationally and calmly from 60 years in the defense industry and at the highest levels of government.

Perry, a graduate of Butler High School, served as secretary of defense in the Clinton administration and was a leading policy expert on nuclear technology from the early days of the Cold War. He was brought to the White House by the Kennedy administration to examine U.S. intelligence on Soviet nuclear capabilities in Cuba during the Cuban Missile Crisis of 1962.

With a new book, “My Journey at the Nuclear Brink,” Perry, now 88, has sobering views of rising nuclear risks that he believes greater than they were during the Cold War.

Perry is also offering his views on U.S. nuclear defenses, namely the triad of weapons based on land, in the air and at sea. He sees the land-based missiles as out of date and no longer needed, arguing that submarine based and aircraft launched nuclear weapons can effectively deter nuclear aggression and respond to any attacks.

In his book, Perry also urges President Obama to scrap plans for a nuclear-equipped cruise missile, which he argues would be destabilizing, inviting overreactions from adversaries who believe a nuclear cruise missile is headed their way when the missile is actually non-nuclear. Escalation to nuclear war, based on mistaken information, would make the world a much more dangerous place.

Perry notes that eliminating land-based nuclear missiles and scrapping of the nuclear cruise missile project would save U.S. taxpayers hundreds of billions of dollars.

Writing in 1999, Perry viewed the collapse of the Soviet Union as reducing the threat of nuclear disaster from a top tier threat. Today, however, he sees nuclear war, of holocaust, as again a real threat, particularly because of the poor diplomatic relations between Washington and Moscow.

Perry’s view that nuclear risks are higher today than during the Cold War is a startling statement. He worries that a miscalculation or overreaction by a nuclear-capable nation or the military response to a terrorist organization setting off a nuclear device in the United States as threatening all of civilization.

Unlike some of today’s presidential candidates, Perry is soft-spoken and well-informed as well as having decades of experience in nuclear weaponry and world affairs. His warnings are frightening, amost too frightening to consider, dwarfing the death toll of terrorist attacks that already have Americans stressed and angry.

Perry’s warnings about the high risks of nuclear disasters and how to minimize them should be understood — by political leaders and average Americans.

The more our leaders and the general public know about today’s nuclear threats and how to reduce the chance of a mistake or miscalculation that escalates to a full-scale war potentially killing millions, the better the chances that such a fate can be avoided.

As frightening as they might be, Perry’s concerns deserve attention. Ignoring his warnings will not make us safer.