Both countries have faced international isolation: North Korea because of its nuclear weapons program, and Syria because of its tactics during a bloody civil war.
Since the beginning of the year, however, Mr. Kim has begun a flurry of diplomatic meetings with leaders in China and South Korea, and he is scheduled to hold a summit meeting with President Trump in Singapore on June 12.
Mr. Kim has not publicly met with another head of state in Pyongyang, the North Korean capital, since taking power, in 2011. He traveled by train to Beijing in March to meet with President Xi Jinping of China, and he crossed the Demilitarized Zone separating the two Koreas to meet with President Moon Jae-in of South Korea in April.
On Thursday, he met with Russia’s foreign minister, Sergey V. Lavrov, as Moscow stepped up efforts to increase its influence in the region ahead of the proposed talks between Mr. Kim and Mr. Trump.
According to the South Korean Foreign Ministry, North Korea established diplomatic relations with Syria in 1966, opening an embassy in Damascus, while Syria opened a mission in Pyongyang in 1969.