North Korea has its own way of acknowledging its troops are joining the Russians in Ukraine without quite saying so. Enter the kid sister of the country’s dictator, Kim Yo-jong, who is known mainly for making nasty statements.

As reported by Pyongyang’s Korean Central Agency, Ms. Kim is saying South Korea and Ukraine “are exactly alike in going about … begging and letting loose ludicrous and reckless remarks against nuclear weapons states that they cannot withdraw.” To which she adds, in her inimitable style, “It seems to be a common feature of bad dogs bred by the U.S.”

Flaunting the deceptively modest title of deputy department director of the central committee of the Workers’ Party of Korea — whose boss, of course, is the general secretary, Kim Jong-un — Ms. Kim is widely believed to be North Korea’s second most powerful leader. Indeed, she may be the source and inspiration for her brother’s increasingly hostile policy toward South Korea, America, and Japan.

Ms. Kim’s latest outburst coincides with confirmation by America’s defense secretary, Lloyd Austin, that North Korea has begun sending troops to support the Russians. Mr. Austin calls it “a very, very serious issue with impacts not only in Europe” but “in the Indo-Pacific as well.”

The disclosure by South Korea’s National Intelligence Service that as many as 3,000 North Korean troops had boarded Russian vessels in North Korea apparently ignited Ms. Kim’s verbal pyrotechnics. Rather than mention North Korea’s role in Ukraine, though, she framed her attack around the North’s claim that the South had sent drones over Pyongyang, calling it “a hideous provocation that can never be pardoned.”

Her fusillade was full of threats to which South Koreans are long accustomed. “Seoul will have to experience first hand so as to know properly how dangerous an act it committed and how terrible and fatal the consequences it brought on itself,” she warned. “The lunatics” of South Korea and Ukraine,” she said, will face “horrible consequences” for risking “a military provocation against a nuclear weapons state.”

In what looked like a carefully contrived one-two blitz, KCNA at the same time  reported that Kim Jong-un had visited an intercontinental missile base, where he warned against America’s nukes. “The U.S. strategic nuclear means pose an ever-increasing threat to the security environment,” KCNA quoted him as saying, while North Korea “takes a thorough and strict counteraction posture of the nuclear forces.”

Like his sister, though, Mr. Kim said nothing about shipping North Korean troops to Russia, where they are believed to be undergoing training before heading to Ukraine. South Korea’s NIS reports 3,000 North Korean troops are there — though the Americans are not confirming the numbers or what they’re doing.

The North Koreans are an elite force, judging from a NIS report cited by a member of the South’s national assembly, Park Sun-won. “Russian instructors believe that North Korean soldiers are fit both physically and mentally,” South Korea’s Yonhap News quoted Mr. Park as saying, “but they lack the understanding of modern warfare, such as drone attacks” — a reflection of the reality that North Korea’s 1.2 million troops are ill-trained for defending the North, much less for war in Ukraine.