North Korean leader said he was filled with 'great joy' after watching soldiers fire at targets on Mahap islet.
An editorial in the ruling party's mouthpiece warned that Trump will have to face a nuclear state.
Kim Yo-jong serves as a vice director of the ruling Workers' Party of Korea's propaganda and agitation department.
The US and South Korea decided to deploy the anti-missile system in July to counter growing North Korean threats.
The embassy has not yet responded to a request for comment on the fate of his predecessor, Hyon Hak-bong.
Sources say the secretive state will test launch the intermediate-range Musudan missile.
According to reports North Korea's first lady Ri Sol-ju was last seen in Pyongyang on 28 March 2016.
A North Korean defector group said the country suspects sabotage by US and South Korean spies.
Special forces of the two countries simulate precision strikes on key North Korean facilities in the exercises.
One of the demands made at the talks was an apology for Pyongyang's attack on the South Korean naval corvette Cheonan in March 2010.
National Intelligence Director James Clapper says the best the Pentagon can hope for is a cap on the North's capability.
The US said it had detected signs that Pyongyang's missile is likely to have exploded soon after launch.
An emergency session was held after Washington and Seoul confirmed the attempt.
North Korean official says a 'pre-emptive nuclear strike is not something the US has a monopoly on'.
One North Korean fisherman was killed and 8 injured in the brief encounter.
Pyongyang reportedly launched the intermediate ballistic missile Musudan, raising tensions in the Korean peninsula.
Pyongyang is particularly high on the US government's radar.
The tentative sanctions against North Korea would cover financial, shipping, trade and immigration sectors.
The warning comes a month after Pyongyang threatened to 'wipe out' the US with a nuclear strike.
Reports suggest that President Park Geun Hye is spending 2 trillion won to build a defector camp.
Reports have claimed that David Sneddon was kidnapped by North Korea and forced to teach Kim Jong-un English.
The drill called Invincible Spirit, will improve maritime interoperability of the two allies, the South Korean Navy said.