As China's patience with North Korea wears thin, US Secretary of State Rex Tillerson says Beijing is ready to step up the punishment.>> We know that China is in communication with the regime in Pyongyang. And in fact, we were told by the Chinese that they informed the regime that if they did conduct further nuclear tests, China would be taking sanctions actions on their own.
>> North Korea has been squeezed by UN sanctions for years, but as Reuters' Michael Martina explains, Beijing going it alone would be a big step.>> If it did go ahead and proceed with such unilateral sanctions, that would be a significant break with what it's done in the past.
China has frequently criticized the United States for carrying out such unilateral sanctions. North Korea gets most of its oil from China, and so Beijing has significant leverage in that area. Other analysts think that oil is a major lifeline for the regime in Pyongyang, and they believe that if China were to cut off oil supplies, it could undermine stability there and potentially lead to collapse.
>> Meanwhile, as Donald Trump warns of a possible major conflict with the North, he's also getting prickly about paying for anti-missile technology that the US is setting up in South Korea. The US says the THAAD system will be operational in the coming days, and in an exclusive interview with Reuters, Trump says Seoul should be footing the bill.
>> Why are we paying a billion dollars? It's a billion dollar system, it's phenomenal. It's the most incredible equipment you've ever seen, shoots missiles right out of the sky. And it protects them and I wanna protect them, we're gonna protect them. But they should pay for that, and they understand that.
>> A top South Korean foreign policy advisor was skeptical ,saying it's impossible for the country to pay for a system that's operated by the U.S. military.