Ambassador to the United Nations Nikki Haley said China has pivoted from its forgiving stance on North Korea to a tougher one.
"It's a new tone coming from China," the former South Carolina governor told "Fox & Friends" on Tuesday.
After pressure from Haley, the United Nations agreed on Saturday to slap sanctions on North Korea, which has tested the international community's patience with threats and missile launch displays.
The new sanctions slash a third of North Korea's $3 billion annual export revenue.
"How many more ICBM [intercontinental ballistic missile] tests do we need to have before we do something?" Haley said she asked countries.
China and Russia both agreed to the sanctions, despite their former reluctance to get tough on the rogue nation. China will be hit the hardest by the new rules because of its close economic relationship with North Korea, and Haley said more sanctions could come in the future.
North Korea is the biggest issue facing United States, the ambassador stated. However, she assured the United States is ready to handle it.
"Don't think that he's not aware and we're not aware of everything that's happening at any given moment," she said. "We know exactly what's going on."
Haley also slammed as "incredibly dangerous" the leaks of intelligence information regarding the United States' military action in the area.
"You're not only just getting a scoop on something. You're playing with people's lives," she warned. "This has got to stop."
America must take a leading role amid the "lack of stability around the world," the ambassador said
"You can't take your eye off of any part of the world right now, and the United States needs to lead in every single one of them."