National security officials shouldn’t forget about the dangers posed by the threat of nuclear terrorism, according to a senior State Department official.

“It is, in a sense, our solemn charge to do everything we can to make sure you don’t have to hear about it because it has been entirely suppressed,” Christopher Ashley Ford, the assistant secretary of state for international security and nonproliferation, told a national security conference Monday. “But it’s still good to talk about nuclear smuggling and nuclear terrorism from time to time, to ensure that everyone remains focused upon keeping this true.”

Ford touted the success of international monitors and investigators in preventing such attacks, but he emphasized that the threat of radiological or nuclear terrorism persists.

Even though “it is trickier than one would imagine” to build such a bomb, it remains all too simple, Ford said, adding that smugglers and prospective terrorists can hope to benefit, finally, from “lax security practices in Russia” and other former Soviet satellite states.

“We cannot be sure how much R/N material is already out there on the black market,” Ford said, in an address delivered Saturday but published Monday. “There are a great many nuclear material scams out there, but not everything is a scam, and there have been enough real cases to make clear that we must take this challenge very seriously indeed.”

Ford noted that “countries have reported 18 seizures of weapon-usable nuclear material” since the fall of the Soviet Union.

“The bad news is precisely what makes the good news of this success so good: Some bad actors do continue to seek such materials, and there is a black market out there in which traffickers do sometimes attempt to buy or steal — and of course, to sell — such things,” he said. ”We need to make sure these people fail.”