Overtures from China and North Korea as Pyongyang held its biggest political event this year show that frosty ties between the communist allies have thawed, say analysts, adding that Beijing's efforts could be aimed at bolstering its credentials as a responsible global power.

Fifth-ranked Politburo Standing Committee member Liu Yunshan, who attended a military parade last Saturday in Pyongyang marking the 70th anniversary of the ruling Workers' Party, is the most senior Chinese leader to visit since the North's power transfer in late 2011. Then-Politburo member Wu Yi appeared at a similar event in 2005.

Mr Liu also passed a letter from President Xi Jinping to North Korean leader Kim Jong Un. Chinese media described it as a step higher than a normal congratulatory message.

In return, North Korea gave Mr Liu the honour of being the only foreign leader in the front row of the parade viewing stand alongside Mr Kim, who reportedly showed restraint in his speech by not making threats about the use of nuclear weapons - an issue that Beijing has expressed concern about in the past.

Chinese state media and observers have quickly described Mr Liu's visit as the start of a new chapter in bilateral ties that have experienced some friction under Mr Xi's leadership since late 2012.

"The Sino-North Korean friendship has encountered some waves and whirlpools, but both sides can generally make sure it is always on the right track... Liu's visit brings new hope to the China-North Korea relationship," wrote the Global Times newspaper in an editorial last Friday.

China was North Korea's ally in the 1950 to 1953 Korean War and has been its main patron and security guarantor in recent decades amid Western sanctions.

But Pyongyang's provocative actions, such as firing ballistic missiles ahead of Mr Xi's visit to South Korea in June last year, reportedly angered Beijing. North Korea was said to be unhappy too that Mr Xi visited South Korea ahead of the North, unlike his predecessors.

China was seen to have punished its isolated neighbour through measures such as tightened exports and stricter banking rules, among others, that further worsened ties.

Dr John Delury, an expert on China and North-east Asia at Yonsei University in Seoul, said China was upset that Mr Kim did not show sufficient respect especially by visiting Beijing after Mr Xi took power.

Mr Liu's visit sends a strong signal that Mr Xi is "swallowing his pride" and taking a more conciliatory approach towards the North, he added, pointing out that the turnaround could have been timed with the warming ties between the two Koreas.

Amid tensions on the Korean Peninsula following North Korea's alleged land mine attacks on South Korean soldiers in August, both sides agreed last month to resume reunions of families separated by the Korean War - seen as a first step towards improving ties.

"China might be thinking that this is a good time to make positive overtures without squandering its good relations with South Korea," Dr Delury told The Straits Times.

Analyst Liu Jia said Mr Liu's visit was also significant as it comes shortly after Mr Xi's visit to the United States, where he met President Barack Obama.

"What Liu brought to Pyongyang could be the outcome of talks between Xi and Obama," he wrote in a commentary.

Others say the olive branch extended to North Korea is part of China's desire to show itself as a responsible global power, despite being a developing country.

Wrote analyst Mao Kaiyun in a commentary: "Liu's discussions with Kim on the Korean Peninsula nuclear issue shows concretely that China loves and protects peace and undertakes seriously its role as a big country in the developing world."

Beijing is propping up the regime in North Korea to prevent a flood of refugees on Chinese soil and also to prevent Washington from moving American troops based in South Korea to China's doorsteps.

But it is also concerned that the North's nuclear ambitions could spark an arms race in North-east Asia and moves by rivals such as the US that would backfire on Chinese interests.

Going forward, observers say Beijing will hope its overtures would get Pyongyang to exercise restraint and also convince the North and other countries like the US to restart six-party talks on the denuclearisation of the Korean Peninsula.

Odds of a meeting between Mr Xi and Mr Kim - who have not met in their current roles unlike Mr Xi and South Korean President Park Geun Hye who have met six times - have risen after Mr Liu's visit.

Early positive signs are emerging, with North Korea sending a 400-strong delegation to an annual trade fair in the Chinese border city of Dandong tomorrowand both sides launching a trade zone there.

But there is no telling whether China can succeed in getting North Korea to toe the line, say analysts.

"The world recognises that North Korea is a tough nut to crack. I don't think it would be a huge liability for China if it fails to do so," said Dr Delury.