North Korea mocked South Korea for being a U.S. “puppet” after U.S. President Donald Trump unilaterally curtailed the two countries’ joint military drills.

“Trump issued a sudden order to reduce the scale of the drill. This has placed Seoul in a poor plight of canceling ‘war games’ it liked very much,” Kim Yo Jong, the sister of North Korean leader Kim Jong Un, said in a statement carried by North Korean state media late Thursday.

She said South Korea “cannot let out a single word of protest at the GIs leaving,” referring to U.S. soldiers.

“This is the inevitable fate of the puppet army,” said Kim, one of the regime’s top spokespeople.

The statement came a day after North Korea rebuffed Trump’s overtures to revive dialogue, with Kim also casting doubt on Trump’s claim to be back in touch with her brother. Pyongyang later fired a barrage of short-range ballistic missiles, in a further sign the North was not willing to engage.

The U.S. and South Korea announced Wednesday that they would conclude their annual summertime exercises this week after Trump ordered the Pentagon to scale them back, citing his good relationship with Kim Jong Un. The drills, which kicked off Monday, were originally planned to run through Aug. 27.

Trump has suggested that the decision, which was not coordinated with South Korea in advance, came in part because of Seoul’s lack of support for his war against Iran.

While South Korea later hailed Trump’s decision as evidence of his determination to promote peace, the move initially appeared to blindside Seoul and raised questions about U.S. security commitment to its ally.

Kim Yo Jong said that Seoul has long “boasted” about the U.S.-South Korea alliance, but the reality was it was akin to “the relation between master and servant.”

“The world witnesses that the U.S. security aids are no longer free of charge,” she added.