'another strong message, threatening....'

President Trump also underscored the importance of close cooperation between Washington and Beijing. Watchers say the call, coming so soon after the two leaders met face-to-face, will serve as a warning to Pyongyang to refrain from further provocations. A state-run media outlet in China reports that Beijing has sent Pyongyang another strong message, threatening to shut down an oil pipeline that supplies free crude oil to the North if the regime conducts a major provocation like a nuclear test or a long-range missile launch.

This question is not about politcs but about usage of commas.

I feel like 'threathening...' should modify message behind without the comma or is there a reason there is a comma between message and threathening?

What do you native English speakers think?

Thank you so much as usual in advance.