The U.S. and China are reportedly discussing a firmer UN response to North Korea's missile and nuclear provocations.

Reuters on Tuesday quoted UN diplomats as saying that the U.S. was negotiating with China the possibility of toughening UN Security Council sanctions on North Korea's repeated ballistic missile launches.

However, it was not immediately clear how open Beijing was to new sanctions. 

Traditionally, the U.S. and China have negotiated new sanctions before involving remaining council members. UN diplomats said the current talks were still just between the two countries.

Some observers say they are discussing stronger action as part of proactive steps to respond to the North in the event that it conducts its sixth nuclear test or another missile launch.

The Reuters report also cited a spokesman for the U.S. Permanent Mission to the UN as saying on Tuesday that Washington is exploring a range of options to respond to Pyongyang's series of provocations with other Security Council colleagues.

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