The UN Security Council is due to meet on Wednesday at the request of the United States to discuss North Korea’s latest missile launches, diplomats said, as Washington pushes the 15-member body to strengthen sanctions on Pyongyang.

North Korea fired a ballistic missile from a submarine on Saturday, South Korea said, the latest in a string of ballistic missile launches, which are banned by the UN Security Council.

The United States has also assessed that North Korea could be ready to conduct a nuclear test as early as this month.

US Ambassador to the United Nations, Linda Thomas-Greenfield, said the United States would like the Security Council to vote during May to further sanction North Korea. However, veto-powers China and Russia have signaled they are opposed to further action.

North Korea has been subjected to UN sanctions since 2006, which the UN Security Council has steadily stepped up over the years in a bid to cut off funding for Pyongyang’s nuclear weapons and ballistic missile programs.

But the hermit Asian state has successfully worked to evade some UN sanctions, according to independent UN sanctions monitors, and North Korean leader Kim Jong Un last month pledged to speed up development of his country’s nuclear arsenal.