North Korea's description of South Korea's president as an "old, insane bitch" destined for violent death may take the rivals' hateful propaganda battle to a new level of hostility, which is saying something for neighbors with such a long, bloody history of hating each other's guts.

The North called President Park Geun-hye's predecessors traitors and even rat-like, but the invectives it throws at the South's first female president tend to be uglier, often casting her relationship with her American allies in crude sexual terms.

Carved in two by the Soviets and Americans at the end of WWII, the halves of the Korean Peninsula fought a vicious war in the early 1950s, and have spent much of the years since then promising, and sometimes trying very hard to engineer, each other's destruction.

North Korea, even as it builds a nuclear arsenal, has in recent decades been outgunned diplomatically, economically and militarily by the richer South; it has therefore relied more on words as a weapon. It has been especially likely to do so under conservative South Korean leaders such as Park and her immediate predecessor, Lee Myung-bak; before Lee took office in 2008, nearly a decade of liberal leaders pushed for cooperation with Pyongyang and sent huge shipments of aid northwards.

The North's attacks may be meant to "reduce hopes for unification, which the North Korean elite really doesn't want, because there's no way they'd keep their privileges on the other side," says Robert Kelly, a political scientist at Pusan National University in the South.

North Korea's overwhelmingly male-dominated culture may have something to do with it as well. Kelly says Pyongyang may not understand that sexist language disgusts many.

Brian Myers, an expert on North Korean propaganda at South Korea's Dongseo University, suggests that young North Korean leader Kim Jong Un may either not remember or not care that his country once carefully tailored its propaganda to influence millions of potential leftist sympathizers in the South.

Myers says that could be bad news for the near future. If it becomes impossible for a South Korean party devoted to accommodation to come to power in Seoul, he says, "I'm afraid we could see the North shift more and more toward outright bullying and intimidation."

Here's a look at North Korea's long history of insults:

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"MURDEROUS DEMON"

In perhaps its lengthiest and harshest verbal attack on Park since she took office in 2013, the North's official Korean Central News Agency on Saturday called her a "tailless, old, insane bitch," a "senile old woman" and a "murderous demon" destined to meet "a sudden and violent death."

This was likely a response to her reaction to the North's recent nuclear test and rocket launch. She closed a jointly run factory park, started missile defense talks with Washington and mentioned the potential for a "regime collapse" in Pyongyang, something North Korea's dictator is extremely sensitive about.

KCNA wrote that Park complains about North Korean nukes, but "takes much pleasure and even throws out her underwear in welcoming the murderous nuclear war devices brought in by the American Yankees."

North Korea previously called Park a "prostitute" and said she lives on the "groin of her American boss." It has frequently questioned her womanhood because she has no children, which the North labels as an "obligation" for women. North Korea also frequently refers to the "swish of her skirts," a Korean phrase used to describe women seen as overly aggressive.

"The swishes of Park Geun-hye's skirt, created by her American boss, are so unpredictable they're dumbfounding," an unnamed spokesman of the North's Joint National Organization of Working People said in a statement last year published by the KCNA. "This is all because the United States' black, hairy hands reach deep into Park Geun-hye's skirt."

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"RAT-LIKE"

The North's propaganda writers spent years attacking Lee, Park's predecessor, by saying he looked like a rat.

In a statement against Lee during his final days as president in January 2013, the North's Committee for Peaceful Reunification of Korea compared Lee and his "treacherous group" to rats five different times, saying that they should be "beaten (to death) in time" and "completely exterminated."

In July 2012, KCNA said the "death-bed frenzy" of Lee's "group of traitors reminds one of the rat-like hoodlums being dragged to gallows."

Lee drew Pyongyang's anger by departing from the rapprochement policies of his two liberal predecessors and slapping the North with broad trade sanctions in 2010 following the sinking of a South Korean warship that killed 46 sailors and which Seoul blamed on a North Korean torpedo attack.

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"FASCIST DICTATOR"

North Korea has described Park Geun-hye as a worse "traitor" than her dictator father, Park Chung-hee, who ruled South Korea for 18 years until his assassination by his spy chief in 1979.

The North attempted to assassinate the elder Park by sending a team of 31 commandos across the border in 1968, but they were stopped near Park's presidential mansion in Seoul.

Shortly after his death, the North's official Rodong Sinmun newspaper called Park a "a truculent fascist dictator" who "plunged South Korea into a sea of blood, arresting, imprisoning and brutally murdering (those) ... who called for the democratization of society and the reunification of the country."

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SLAPS AGAINST U.S.

North Korea often extends its insults to the presidents and other key officials of the United States, which Pyongyang labels as an imperialist aggressor and puppet master of the Seoul government.

The North hurled racist insults at U.S. President Barack Obama more than once, with Pyongyang's powerful National Defense Commission calling him a "monkey in a tropical forest" in December 2014 over the hacking row involving the movie "The Interview," a comedy that depicts Kim's assassination.

The North's state media has called U.S. Secretary of State John Kerry a wolf with a "hideous" lantern jaw, and his predecessor, Hillary Clinton, as a "funny lady" who sometimes "looks like a primary schoolgirl and sometimes a pensioner going shopping."

Former U.S. President George W. Bush, who in 2002 bracketed North Korea with Iran and pre-war Iraq as part of an "axis of evil," was labeled as a "world dictator," and a "hooligan bereft of any personality as a human being." His vice president, Dick Cheney, was described by the North in 2005 as "the most cruel monster and bloodthirsty beast as he has drenched various parts of the world in blood."