"Through the practice this time, South Korean and US Air Forces showed off the allies resolve for strong retaliation against North Korea's nuclear and missile threats", it said.
The North Korean party anniversary passed without any missile launches or nuclear tests, but officials are wary the North could engage in more provocations at any time, especially with China to begin its all-important Communist Party Congress on October 18.
A South Korean lawmaker says North Korean hackers stole highly classified military documents that include U.S.
The U.S. military conducted another show of force to North Korea on Wednesday as long-range B-1 bombers flew a nighttime mission over the Sea of Japan accompanied by Japanese and South Korean fighter aircraft.More news: Doesn't President Donald Trump Say "Puerto Rico" In Such A Strange Way?
Two U.S. B-1 bombers carried out a training exercise on Tuesday with Japanese and South Korean military aircraft in the vicinity of the Sea of Japan, the U.S. military said, amid growing tension over North Korea's missile and nuclear programs.
It came days after he said that diplomatic efforts with North Korea have consistently failed, adding that "only one thing will work".
"There is an urgent need for the military to change and update parts that were stolen by North Korea", Lee said.
Pyongyang has denied responsibility for the cyberattacks in its state media, criticising Seoul for "fabricating" claims about online attacks.
Trump and North Korean leader Kim Jong-un exchanged heated rhetoric in recent weeks. But Kim, the third generation of his family to rule, is officially revered in the North, and any suggestion of removing him from power is taken extremely seriously in Pyongyang.More news: San Juan Mayor Labels Trump "Miscommunicator-in-Chief" After "Insulting" Visit
U.S. B-1 bomber, center, flies over Osan Air Base with US jets in Pyeongtaek, South Korea, Tuesday, Sept. 13, 2016.
He revealed that around 235 gigabytes of military documents had been stolen from the Defence Integrated Data Centre, and that 80% of them have yet to be identified.
These plans had likely not been classified properly but defence ministry officials told Rhee the hacked documents were not of top importance, he said.
"Our country has been unsuccessfully dealing with North Korea for 25 years, giving billions of dollars & getting nothing".More news: Robert Kirkman confirms The Walking Dead and Fear the Walking Dead crossover