NEW YORK — The United States is “done talking about North Korea” and China is aware they must act, U.S. Ambassador to the United Nations Nikki Haley said on Sunday after North Korea fired its second long-range missile this month and amid a push by Washington to impose stronger U.N. sanctions on Pyongyang.

“Done talking about North Korea. China is aware they must act. Japan and South Korea must increase pressure. Not only a U.S. problem. It will require an international solution,” Haley posted on Twitter.

She then posted a link to photos of the United States, Japan and South Korea conducting bomber jet drills over the Korean Peninsula on Sunday. The United States flew two supersonic B-1B bombers as a show of force after Pyongyang fired an intercontinental ballistic missile on Friday.

The United States has been in talks with North Korean ally China on a draft U.N. Security Council resolution to impose stronger sanctions on North Korea. Haley gave China a draft text after North Korea’s July 4 ICBM test.

Haley said last Tuesday that the United States had been making progress with China.

Some diplomats had expected the United States, Japan and South Korea to ask for the 15-member U.N. Security Council to meet on Monday over the test, but no such request has yet been made.

Such a meeting would set the stage for a likely showdown between the United States and Russia over whether Friday’s launch was a long-range rocket test.

Diplomats say China and Russia only view a long-range missile test or nuclear weapon test as a trigger for further possible U.N. Security Council sanctions.

The Pentagon and South Korean military believe Friday’s test was an ICBM. However, a Russian Defence Ministry official said Moscow’s data indicated it was only a medium-range missile.

The United States and Russia have waged rival campaigns at the U.N. Security Council over the type of ballistic missile fired by North Korea on July 4. Western powers said it was an ICBM, while Russia said it was medium-range.

North Korea has been under U.N. sanctions since 2006 over its ballistic missile and nuclear programs and the Security Council has ratcheted up the measures in response to five nuclear weapons tests and two long-range missile launches.

Haley has said some options to strengthen U.N. sanctions were to restrict the flow of oil to North Korea’s military and weapons programs, increasing air and maritime restrictions and imposing sanctions on senior officials.

Traditionally, the United States and China have negotiated sanctions on North Korea before formally involving other Security Council members.

Kim Jong Un supervises launch

North Korean leader Kim Jong Un personally supervised the midnight launch of the missile on Friday night, and he said it was a “stern warning” for the United States that it would not be safe from destruction if it tries to attack, the North’s official KCNA news agency said.

North Korea’s state television broadcast pictures of the launch, showing the missile lifting off in a fiery blast in darkness and Kim cheering with military aides.

“The test-fire reconfirmed the reliability of the ICBM system, demonstrated the capability of making a surprise launch of the ICBM in any region and place any time, and clearly proved that the whole U.S. mainland is in the firing range of the DPRK missiles, [Kim] said with pride,” KCNA said.