President Donald Trump said Thursday he is "very disappointed" following a report that China may have run afoul of international sanctions by providing oil to North Korea.

In a tweet, Trump warned that "there will never be a friendly solution" to North Korea's nuclear and missile programs "if this continues to happen!"

Trump tweet

A South Korean newspaper reported that Chinese and North Korean ships linked up at sea to provide oil to Kim Jong Un's regime. The report comes as the United Nations tries to choke off most of Pyongyang's oil supply amid continued aggressive actions by North Korea.

China has denied illegally providing oil, according to Reuters.

"The situation you have mentioned absolutely does not exist," Chinese Defense Ministry spokesman Ren Guoqiang said at a briefing, according to the wire service.