North Korean dictator Kim Jong Un is once again threatening war with South Korea, Japan and the U.S. He assures us his ballistic missiles will soon bear nuclear warheads.

Last week, aircraft loyal to Syria’s Assad dictatorship dropped nerve agent bombs on a civilian neighborhood. The U.S. retaliated for the war crime with a classic punitive strike. American cruise missiles hammered the airfield used by Assad regime jets.

North Korea and Syria present the world with different diplomatic and military challenges. They differ geographically — East Asia and the Pacific basin versus Southwest Asia. They differ in historical origin.

Yet North Korea and Syria have some fascinating and frightening similarities.

Let’s start with this one: The current governments of North Korea and Syria are both hereditary dictatorships. North Korea’s Kim regime is a hereditary totalitarian military autocracy with Communist trappings. The regime’s progenitor, Kim Il Sung, began the Korean War in 1950 when his forces invaded South Korea. Thanks to help from Communist China, the war ended in a stalemate, leaving two heavily armed and determined adversaries confronting one another across a fortified armistice line.

Kim Il Sung acquired chemical weapons and began North Korea’s nuclear weapons and ballistic missile programs. He groomed his son, Kim Jong Il, to succeed him, which he did in 1994 when Kim The First died. Kim The Second died in 2011. Current dictator Kim Jong Un assumed Pyongyang’s military throne.

Hafez al-Assad, a former Syrian Air Force officer, seized power in Syria in 1970 by toppling the ruling dictator. In 1971 he officially installed himself as president and began three decades of ruthless one-man rule. Assad The First allied Syria with the totalitarian Soviet Union. He wanted modern weapons, ostensibly to wage war with Israel but maintaining his regime was the first order of business. Assad The First acquired chemical weapons and began a ballistic missile program.

Assad The First originally pegged his younger brother, Rifaat al-Assad, as his successor, but the two had a falling out when Rifaat tried to succeed Hafez too soon. So Hafez named his eldest son, Bassel al-Assad, as heir apparent. Bassel was an army officer. But in 1994, Bassel died in an accident. His younger brother, Dr. Bashar al-Assad, became the heir and was given a senior military position. When Hafez died in 2000, Bashar took the throne.

Like the Kim dynasty, the Assad dynasty has military origins and deep military ties. However, its deepest roots are sectarian and tribal — no surprise in sectarian- and ethnically-fragmented Syria. The Assads are Alawites, a minority Shia Muslim sect.

Syria is a hodgepodge of ethnic and sectarian groups. In comparison, North Korea is an ethnic monolith. However, both regimes need war in order to exist. They rely on war to eliminate their political opposition and to solidify support for their respective regimes.

Modern dictatorships usually conjure some type of philosophy or appeal to religious doctrine to explain and justify their tyrannies. The Assad dynasty claims to be secular, but among Syrian Alawites and Shias it sells itself as a defender of the faith. This Shia link is one reason Iran’s radical Shia Muslim dictatorship supports the Assads and provides them with Shia fighters from the Lebanese Hezbollah Shia terror organization.

Kim Il Sung created a secular religion called “Juche.” It combines nationalism, collectivism and shards of Oriental and Western philosophies. Juche emphasizes the uniqueness of the Korean character and the need to unify the Koreas under the Juche banner and the Kim dynasty’s rule.

Let’s end with this sobering similarity: North Korea and Syria have long-standing relationships with powerful authoritarian states possessing UN Security Council vetoes, China and Russia respectively. That means in a crisis involving either state, the U.S. is the only effective major power counterweight.

Austin Bay is a syndicated columnist and author.