* U.S. supersonic bombers fly with South Korean, Japanese fighter jets
* Trump "disappointed" in China; has done "nothing" on North Korea
* UN Ambassador Haley: China, Japan, South Korea must do more (Adds comment from U.S. ambassador to the United Nations, U.S. Senator Feinstein, and background from intelligence experts)
By James Pearson and Michelle Nichols
SEOUL/NEW YORK, July 30 (Reuters) - The United States flew two supersonic B-1B bombers over the Korean peninsula in a show of force on Sunday and the U.S. ambassador to the United Nations said China, Japan and South Korea needed to do more after Pyongyang's latest missile tests.
North Korea said it conducted another successful test of an intercontinental ballistic missiles (ICBM) on Friday that proved its ability to strike America's mainland, drawing a sharp warning from U.S. President Donald Trump.
Trump's ambassador to the United Nations Nikki Haley said on Twitter on Sunday that the United States was "done talking" about North Korea, which was "not only a U.S. problem."
"China is aware they must act," Haley said, urging Japan and South Korea to increase pressure and calling for an international solution.
China, the North's main ally, said it opposed North Korea's missile launches, which it said violate UN Security Council resolutions designed to curb Pyongyang's banned nuclear and missile programmes.
"At the same time, China hopes all parties act with caution, to prevent tensions from continuing to escalate," China's foreign ministry said in a statement on Saturday.
Early in his presidency, Trump met with Chinese President Xi Jinping and had expressed hope Beijing would use its economic clout to curb North Korea's nuclear ambitions.
But on Saturday, Trump said on Twitter that he was "very disappointed in China" which he said profits from trade with the United States but does "NOTHING for us with North Korea, just talk. We will no longer allow this to continue," he said.
DIRECT RESPONSE
North Korean leader Kim Jong Un personally supervised the midnight test launch of the missile on Friday night and 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 missile test came a day after the U.S. Senate approved a package of sanctions against North Korea, Russia and Iran.
The B-1B flight was a response to the missile test and the July 3 launch of the "Hwasong-14" rocket, the Pentagon said. The bombers took off from a U.S. air base in Guam, and were joined by Japanese and South Korean fighter jets during the exercise, according to the statement.