The US ambassador to the United Nations, Ambassador Linda Thomas-Greenfield, said Sunday that China would cross a “red line” if the country decided to provide lethal military aid to Russia for its invasion of Ukraine.

“We welcome the Chinese announcement that they want peace because that’s what we always want to pursue in situations like this. But we also have to be clear that if there are any thoughts and efforts by the Chinese and others to provide lethal support to the Russians in their brutal attack against Ukraine, that is unacceptable,” she told CNN’s Pamela Brown on “State of the Union.”

“That would be a red line,” she warned.

With confirmation from US officials familiar with the intelligence, CNN reported prior that ''the US has begun seeing “disturbing” trendlines in China’s support for Russia’s military, and there are signs that Beijing wants to “creep up to the line” of providing lethal military aid to Russia without getting caught.''

Meanwhile, Western leaders have reacted nervously to a Chinese peace plan for Ukraine due to be revealed this week.

China’s senior diplomat Wang Yi spoke at the Munich Security Conference and announced that China would launch its peace initiative and has already been consulting Germany, Italy and France on its proposals but at the same time, he also said the legitimate security interests of Russia needed to be respected.

 Secretary of State Antony Blinkenis was also in Germany for the Munich Security Conference and he spoke face-to-face with Wang on the consequences China would face if they were to provide weapons, ammunition, or other lethal aid to Russia.