BEIJING/SEOUL -- China is preparing to send an art troupe to North Korea, possibly this month, in a display of solidarity after the neighbors shored up their relations with a surprise summit in late March.

Other, deeper changes may be afoot as well.

A diplomatic source cited speculation that China may do more to stop North Koreans from escaping into China, and loosen economic sanctions against Pyongyang. Experts note that if China were to secretly increase oil supplies to the North through a pipeline, it would be difficult for the international community to prove it.

Sources from both China and North Korea said the art troupe could be dispatched around April 15, when the North celebrates the birth of founding father Kim Il Sung. The occasion is known as the Day of the Sun.

This would follow a recent visit to Pyongyang by a contingent of South Korean entertainers, including high-profile singers. China apparently wants to show the world that it is back on friendly terms with the North.

Cultural exchanges between the two countries used to be relatively common. A Chinese People's Liberation Army song and dance ensemble performed in Pyongyang, among other examples. But the relationship grew strained after Chinese President Xi Jinping visited South Korea in 2014.

During last month's summit between Xi and North Korean leader Kim Jong Un, the North expressed its willingness to rejoin the six-party talks on denuclearization. China appears to be showing North Korea a degree of consideration in return.

A South Korean human rights group said Chinese authorities have detained more than 20 North Korean defectors since late March. This suggests China may be willing to meet North Korean requests to crack down on escapees and send them back.