President Donald Trump on Sunday condemned North Korea’s latest weapons test, saying the nation’s actions were very “hostile and dangerous” to the United States, and an embarrassment to China.

Early Sunday, the regime led by Kim Jong Un claimed on state television that it had successfully conducted a test of a hydrogen bomb that could be carried by an intercontinental ballistic missile. Though that claim was not immediately verified by U.S. authorities, seismic activity within North Korea suggested a large detonation consistent with a nuclear test.

“North Korea’s supreme dear leader signed the order to test hydrogen bomb to be fitted to the ICBM and accordingly North Korea has tested a hydrogen bomb at noon on Sept. 3rd (North Korea time) and succeeded totally,” a female newscaster said on the KCNA televised announcement, according to an NBC News translation.

Responding on Twitter, Trump called the country “a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success.”

..North Korea is a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success.

In recent days, South Korea has stepped up its defensive posture, joining the U.S. in a series of military exercises designed as a show of force to dissuade Pyongyang.

Trump has repeatedly insisted that all options were on the table, raising the possibility of a military confrontation. Yet just last month, South Korean President Moon Jae-In issued a blunt warning to the U.S., saying a unilateral military strike against the North would not be advisable unless it was coordinated with his country.

“South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing,” Trump tweeted on Sunday.

–Leslie Shaffer contributed to this article.