North Korea has launched about 10 short-range ballistic missiles towards the sea, South Korea’s military said, a day after Pyongyang shrugged off Donald Trump’s order to scale back US military drills with South Korea in an apparent attempt to resume diplomacy.

The joint chiefs of staff said the missiles were launched from the region of Pyongyang at around 5pm (08.00 GMT) on Thursday towards North Korea’s eastern waters.

The military said South Korea had bolstered its surveillance and was closely coordinating information on the launches with the US and Japan.

South Korea’s presidential national security council held an emergency meeting, after which it issued a statement urging North Korea to halt ballistic missile launches, which are banned under UN security council resolutions.

The Japanese prime minister’s office said earlier that it had detected a suspected missile launch.

On Wednesday, the South Korean and US militaries said they were scaling back their 11-day Ulchi Freedom Shield exercises. Donald Trump had ordered the Pentagon to “substantially reduce” the exercises just before they began on Monday. Explaining his reasons for the decision, the US president cited what he said was a good relationship with North Korea’s leader, Kim Jong-un, and South Korea’s refusal to support him over the war against Iran.

Kim Yo-jong, the influential sister of the North Korean leader, dismissed Trump’s overture on Wednesday, saying it was not worthy of comment.

“The provocative, aggressive nature of the drills won’t change even though their duration and size were reduced,” she said. “If the US calculates that it can propagate its recent measure as one of so-called good faith, they will not get the desired answer.”

She highlighted a series of other military drills carried out by the US and South Korea earlier this year and South Korea’s push to introduce nuclear-powered submarines.

However, Kim Yo-jong refrained from the typical North Korean reaction of fiery rhetoric, and said personal relations between her brother and Trump were “still excellent”. That could signal a desire by Pyongyang to wait for Trump to make bigger concessions before returning to talks.

She denied Trump’s claim that Kim Jong-un had responded to his request for a conversation.

When asked by reporters on Wednesday if he would be meeting Kim Jong-un this year, Trump said: “Yeah, I will be.” He would not answer a question about whether he was exchanging letters with Kim, but said he got along with him.