SEOUL (Reuters) - North Korean leader Kim Jong Un sent a rare congratulatory message to Chinese President Xi Jinping on Wednesday at the end of China’s Communist Party Congress, wishing him “great success” as head of the nation, the North’s state media said.

A man watches a news broadcast of China's President Xi Jinping and other new Politburo Standing Committee members attending a meeting in Beijing, outside a commercial building in Hong Kong, China October 25, 2017. REUTERS/Bobby Yip

The friendly gesture by the North Korean leader, who seldom issues personal messages, comes as China is being urged by the international community to do more to rein in the North’s missile and nuclear tests that have raised tensions globally.

Xi became China’s most powerful leader since Mao Zedong at the all-important week-long congress.

“It expressed the conviction that the relations between the two parties and the two countries would develop in the interests of the peoples of the two countries,” the North’s state-run central news agency said in a statement on Thursday, citing the message sent by Kim to Xi.

“The Chinese people have entered the road of building socialism with the Chinese characteristics in the new era” under the guidance of Xi, the message said.

The two countries often exchange routine diplomatic correspondence and ceremonial letters to each other on political anniversaries or political promotions, although personal messages to and from the leaders tend to be few.

Analysts said it was too early to tell whether or not ties between the two countries were warming up.

“Congratulatory messages between North Korea and China are an old story and reading too much into the message exchanged would be a one-sided analysis,” said Yang Moo-jin, professor at the University of North Korean Studies in Seoul.

“It’s what they usually do and not surprising at all.”

China is the North’s sole major ally, and accounts for more than 90 percent of trade with the isolated country.

Beijing has been called upon by several countries, especially the United States, to step up its efforts to curb North Korea’s ambitions towards building a nuclear-tipped ballistic missile that can reach the United States.

It has shown it is irritated with Pyongyang following the isolated state’s numerous missile launches and nuclear tests, repeatedly calling for restraint and urging all sides to speak and act carefully.

Chinese Foreign Ministry spokesman Geng Shuang said at a regular briefing on Thursday that China had received congratulatory messages from many countries and parties, including one from North Korea.

“China and North Korea are close neighbors and have a tradition of friendly contact,” he said, without elaborating.

China has said it will strictly enforce U.N. Security Council sanctions banning imports of North Korean coal, textiles and seafood, while cutting off oil shipments to the North.

North Korea has not engaged in any missile or nuclear provocations since mid-September, although it tends to test fewer missiles late in the year for unexplained reasons.

“North Korea has been walking a diplomatic tightrope by taking advantage of strategic mistrust between China and Russia, but it has not been easy as Beijing has sternly responded to its nuclear and missile provocations,” said Kim Han-kwon, a professor at the Korea National Diplomatic Academy in Seoul.

“China’s party congress is over, but Kim Jong Un’s concerns will only continue to deepen. The most significant event at hand is the upcoming summit between Xi and (U.S. President Donald) Trump,” said Kim.