Russia and North Korea have had a complicated relationship over the decades

SEOUL, South Korea (AP) — President Vladimir Putin is in North Korea for a summit with its leader, Kim Jong Un, as the two nations deepen their cooperation.

The visit comes amid growing concerns about an arrangement in which Pyongyang provides Moscow with badly needed munitions to fuel Russia’s war in Ukraine in exchange for economic assistance and technology to enhance the threat posed by Kim’s nuclear weapons and missile program.

Despite their often aligning interests, relations between Russia and North Korea have experienced highs and lows. Some key events:

1945-1948 — Japan’s colonial rule of the Korean Peninsula ends with Tokyo’s World War II defeat in 1945 but the peninsula is eventually divided into a Soviet-backed north and a U.S.-backed south. The Soviet military installs future dictator Kim Il Sung, a former guerrilla leader who fought Japanese forces in Manchuria, into power in the North.

1950-1953 — Kim Il Sung’s forces launch a surprise attack on the South in June 1950, triggering the Korean War. The conflict brought in forces from the newly created People’s Republic of China, aided by the Soviet air force. Troops from South Korea, the United States and other countries under the direction of the United Nations battle to repulse the invasion. A 1953 armistice stops the fighting and leaves the Korean Peninsula in a technical state of war.

Mid-1950s though 1960s — The Soviet Union continues to provide economic and military assistance to North Korea, but their relations decline as Kim Il Sung violently purges pro-Soviet and pro-Chinese factions within the North’s leadership to consolidate his power. Moscow reduces its aid but does not cut it off until the end of the Cold War.

1970s — As a rivalry between the