North Korea and China are marking the 75th anniversary of their relationship as outsiders question their relationship

SEOUL, South Korea (AP) – The leaders of North Korea and China marked the 75th anniversary of diplomatic relations on Sunday, exchanging messages expressing hope for closer ties, outsiders said questions about their relationship.

The message exchange came as North Korea and Russia are rapidly expanding cooperation, while China appears to be keeping its distance. Experts say the level of exchanges and commemorative programs between North Korea and China in the coming months will give an indication of the exact state of their ties.

According to the official Korean Central News Agency, in a message sent to Chinese President Xi Jinping, North Korean leader Kim Jong Un said that his government “will constantly strive to consolidate and develop friendly and cooperative relations” between the two countries.

Xi, in his message to Kim, said China was ready to jointly promote “stable and further progress of the socialist cause in both countries,” KCNA said.

Since North Korea and China established diplomatic relations on October 6, 1949, their relationship has often been described as “close as lips and teeth.” China, North Korea’s largest trading partner and major aid provider, is suspected of avoiding fully implementing U.N. sanctions on North Korea and sending secret aid shipments to help its impoverished neighbor stay afloat and continue to serve as a bulwark against U.S. influence in Korean Peninsula.

However, many observers say China is reluctant to form a trilateral, anti-Western alliance with North Korea and Russia because it prefers a stable regional security environment to address its many economic challenges and maintain relations with Europe and its Asian neighbors.

North Korea and Russia have become significantly closer amid widespread outside suspicions that North Korea has provided Russia with conventional weapons for the war in Ukraine in exchange for military and economic aid. During a meeting in Pyongyang in June, Kim and Russian President Vladimir Putin signed an agreement pact providing for mutual military assistance if either country was attacked, in what was considered the largest defense agreement between the two countries since the end of the Cold War.

North Korea is embroiled in confrontations with the US, South Korea and their partners over its advancing nuclear program. Kim said he was forced to expand both nuclear and conventional ability to deal with US-led security threats.

On Sunday, KCNA reported that Kim supervised artillery exercises conducted by military academy cadets. After watching the drills, Kim said training programs at the military academy must focus on “guerrilla warfare tactics of destroying enemies through rapid mobile and surprise operations,” according to KCNA.