North Korea's National Defense Commission has penned a letter to South Koreans saying it is determined "to create an atmosphere of reconciliation and unity," the isolated nation's state news agency reported.

In the letter, the commission also vowed to work to "completely halt hostile military acts, realize the reunion of separated families and relatives, … and re-energize multi-faceted north-south cooperation and exchanges."

But there was a catch, as the officials pressed for Pyongyang's peace proposals, including stopping an upcoming U.S.-South Korea military drill and defending its own "precious nuclear force for self-defense."

The open missive was carried by KCNA, which for years has featured reports deriding South Korea and its longtime ally, the United States.

It touts a proposal brought forward by North Korean authorities last week that signals "the steadfast will of its army and people to improve the North-South relations by concerted efforts of the two sides, not asking about all inglorious happenings in the past."

"The North-South relations will be improved on a solid basis only when both sides take realistic measures to prevent impending nuclear disasters with concerted efforts of the Korean nation," the commission wrote in a letter reportedly written Thursday and put out the next day.

South Korean Unification Ministry spokesman Kim Eui-do said Friday morning that his government is working on a response to the letter.

Still, many in Seoul and elsewhere have long had difficulty gauging Pyongyang's motives and intentions.

South Korean President Park Geun-hye told CNN's Paula Hancocks earlier this month that she feels it is now especially hard to make sense of what's happening or will happen next inside North Korea. She referenced the recent unforeseen execution of North Korean leader Kim Jong Un's uncle and perceived protector, Jang Song Thaek, as proof.

"North Korea has always been very unpredictable, but the level of unpredictability has, in fact, (been) exacerbated," Park said. "I'm concerned about deepening volatility."

North Korea's latest letter touches on many of the same points, and highlights similar proposals, to one addressed to South Korean authorities last week. Nonetheless, it appears to have a slightly softer tone than that missive, and certainly seems more conciliatory and less combative than many statements in recent years.

The relationship between Seoul and Pyongyang has risen to new levels of anxiety and danger as North Korea has developed its nuclear and long-range missile programs despite widespread international opposition.

Early last year, for example, tensions were simmering near the boiling point: North Korea's army declared the armistice ending the 1950 to 1953 armed conflict to be invalid on March 11, and a few weeks later, state news reported that Pyongyang had entered a "state of war" and threatened to "dissolve" the U.S. mainland.

"Any issues regarding North and South will be treated in accordance to the state of war," North Korea's government said in a special statement carried by KCNA.

Just last week, a government spokesman issued a statement noting leader Kim Jong Un's "sincere stand to ease tension and ensure peace" while also slamming "ill-boding, provocative remarks … from South Korea" as well as "powder-reeking war exercises" involving the United States.

"The recent announcement of the huge DPRK-targeted war drills by the U.S. and puppet warmongers is a total denial of the improvement of the North-South ties and dialogue and is little short of the declaration of a total nuclear stand-off," said the spokesman.

The United States, at least, won't call off its joint military exercises starting next month with South Korea, despite Pyongyang's pleas.

"We don't plan to stop the exercises," Adm. Samuel Locklear III, head of the U.S. Pacific Command, told reporters Thursday. "The exercises are … a cornerstone of how we train and maintain the alliance… It's not a change. We do these every year."

Notably, North Korea's latest message jabbed directly — as it has in the past — at South Korea's international allies.

And the commission didn't entirely spare Seoul either, chiding leaders there for not embracing its "important" initiative.

"Regretfully, … the South Korean authorities still remain unchanged in its improper attitude and negative stand towards the proposal," the letter states. "What is most important for mending the inter-Korean ties is to have a proper attitude and stance towards this issue."