CHINA and Russia joined diplomatic forces yesterday and called on North Korea, South Korea and the United States to sign up to a de-escalation plan designed to defuse tensions around Pyongyang’s missile program.

The plan would see North Korea suspend its ballistic missile program and the US and South Korea simultaneously call a moratorium on large-scale missile exercises, both moves aimed at paving the way for multilateral talks.

The initiative was set out in a joint statement from the Russian and Chinese foreign ministries issued shortly after President Vladimir Putin and President Xi Jinping held wide-ranging talks in the Kremlin.

“The situation in the region affects the national interests of both countries,” the joint statement said. “Russia and China will work in close coordination to advance a solution to the complex problem of the Korean Peninsula in every possible way.”

North Korea said yesterday that it had successfully test-fired an intercontinental ballistic missile (ICBM) for the first time, on a trajectory that experts said could allow a weapon to hit the US state of Alaska.

Beijing and Moscow used the same joint declaration to call on Washington to immediately halt deployment of its THAAD anti-missile system in South Korea, a move Washington says is necessitated by the North Korean missile threat.

The statement said Washington was using North Korea as a pretext to expand its military infrastructure in Asia and risked upsetting the strategic balance of power in the area.

“The deployment ... of THAAD will cause serious harm to the strategic security interests of regional states, including Russia and China,” the statement said.

“Russia and China oppose the deployment of such systems and call on the relevant countries to immediately halt and cancel the process of deployment.”

North Korea ballistic missile test is a potential game-changing development in what may be the world’s most dangerous nuclear standoff and a direct rebuke to US President Donald Trump’s earlier declaration that such a test “won’t happen!”

North Korea’s Academy of Defense Science said the test of an ICBM — the Hwasong-14 — marked the “final step” in creating a “confident and powerful nuclear state that can strike anywhere on Earth.”

Unless outsiders retrieve parts of the missile, it will be difficult to confirm many details.

North Korea’s weapons program is perhaps the most closely held state secret.

North Korea has previously launched satellites in what critics said were disguised tests of its long-range missile technology.

A test-launch of an ICBM, however, would be a major step in developing nuclear-armed missiles that could reach anywhere in the US.

The launch sends a political warning to Washington and its chief Asian allies, Seoul and Tokyo, while also allowing North Korean scientists a chance to perfect their still-incomplete nuclear missile program.

It came on the eve of the US Independence Day holiday, days after the first face-to-face meeting of the leaders of South Korea and the US, and ahead of a global summit of the world’s richest economies.

US, South Korean and Japanese officials say the missile flew for about 40 minutes and reached an altitude of 2,500 kilometers, which would be longer and higher than any similar test previously reported.

North Korea said the missile flew as high as 2,802 kilometers before hitting a designated target in the ocean about 933 kilometers from the launch site in the northwest.

Before North Korea’s announcement of an ICBM, South Korean analysts said it was likely that it was a retest of one of two intermediate-range missiles launched earlier this year.

One US missile scientist, David Wright, estimated that the highly lofted missile, if the reported time and distance are correct, could have a possible maximum range of 6,700 kilometers, which could put Alaska in its range, if fired at a normal trajectory.

North Korea has a reliable arsenal of shorter-range missiles and is thought to have a small arsenal of atomic bombs, but is still trying to perfect its longer-range missiles.

Some outside civilian experts believe North Korea has the technology to mount warheads on shorter-range Rodong and Scud missiles that can strike South Korea and Japan, where about 80,000 American troops are stationed. But it’s unclear if it has mastered the technology needed to build an atomic bomb that can fit on a long-range missile.

Soon after the morning launch, US President Trump responded on Twitter.

“North Korea has just launched another missile. Does this guy have anything better to do with his life? Hard to believe that South Korea and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!”

“This guy” presumably refers to North Korean leader Kim Jong Un.

After North Korea claimed earlier this year that it was close to an ICBM test launch, Trump took to Twitter and said: “It won’t happen!”

The missile test could invite a new round of international sanctions, but North Korea is already one of the most sanctioned countries on Earth.

UN Security Council resolutions ban it from engaging in any ballistic activities.

Since late 2012, North Korea has placed two satellites into orbit with long-range rockets, each time triggering new UN sanctions and worldwide condemnation.

Last year, North Korea conducted its fourth and fifth atomic bomb tests and claimed a series of technical breakthroughs in its efforts to develop long-range nuclear missiles.

The fifth nuclear test in September was said to be its most powerful atomic detonation to date.

On May 14, North Korea launched a Hwasong-12 missile which its state media said flew as high as 2,111 kilometers and landed in a targeted area in the ocean about 787 kilometers from the launch site.

On May 21, North Korea tested a Pukguksong-2, which traveled a distance of about 500 kilometers.

Also yesterday, China and Russia signed an outline of bilateral space cooperation on such fields as rocket engines, Earth observation and moon exploration during Xi’s state visit to Russia.