As part of the exercise, two American B-1 bombers and South Korean and Japanese fighter jets flew over the Korean Peninsula. There are also serious concerns about North Korea's cyberwarfare capabilities, but the USA has been carrying out operations of its own to counter North Korean cyber operations in Northeast Asia and elsewhere. Such flights by the powerful aircraft based in Guam incense the North, which claims they are preparation for war; Pyongyang has threatened to send missiles into the waters around Guam.
President Trump hosted a discussion on options to respond to any North Korean aggression, or, if necessary, to prevent Pyongyang from threatening the U.S. and its allies with nuclear weapons, the White House said in a statement.
However, Trump said he still had confidence in the secretary of state. Some military experts believe that power supply problems make it hard for North Korea to turn on its air defense radars for 24 hours a day and also that the systems might struggle to effectively track advanced warplanes such as B-1Bs, which have low radar-cross sections.
The bombers took off from the US Pacific territory of Guam on Tuesday night, before entering South Korean airspace and conducting firing exercises over the East Sea and Yellow Sea, South Korea's military said.
Two supersonic United States bombers have flown over the Korean peninsula in a "show of force" despite Kim Jong-Un's threats to shoot them down.
Trump has engaged in an escalating war of words with North Korean strongman Kim Jong-Un, trading insults amid rising tensions between the two nuclear-armed rivals.
"There is an urgent need for the military to change and update parts that were stolen by North Korea", Lee said.
The North's missile and nuclear capabilities have made significant progress under Kim, who on Saturday told party officials that the country's atomic weapons were a "treasured sword" to protect it from aggression.
Lee said that 235 gigabytes of military documents were taken, but the military has yet to identify 80 percent of the documents that were compromised.
North Korea has launched two missiles over Japan and conducted its sixth and biggest nuclear test in recent weeks in defiance of U.N. sanctions as it races towards its goal of developing a nuclear-tipped missile capable of hitting the United States.
"Our country has been unsuccessfully dealing with North Korea for 25 years, giving billions of dollars & getting nothing".