Rhee told CNN on Tuesday that the documents stolen included the South Korea-US wartime operational plan and a document that includes procedures to "decapitate" the North Korean leadership.
North Korea tested two intercontinental ballistic missiles in July and conducted its sixth and most powerful nuclear test in September.
"Although I will not comment on intelligence matters or specific incidents related to cyber intrusion, I can assure you that we are confident in the security of our operations plans and our ability to deal with any threat from North Korea", Pentagon spokesman Colonel Robert Manning told reporters.
United States president Donald Trump has "lit the wick of war" with North Korea and his country will be made to pay with "a hail of fire", a Russian news agency quoted North Korea's foreign minister as saying on Wednesday.
This comes after US President Donald Trump last night discussed a "range of options" with his national security team to respond to North Korea's recent nuclear tests.
Rhee, now a member of the National Assembly's committee for national defence, said about 80 percent of the hacked data has not yet been identified, but that none of the information was expected to have compromised the South Korean military as it was not top classified intelligence.
Same-store slowdown cools Domino's rally
Return on assets is 34.00% and Return on equity (ROE) is -13.30% while it's Return on Investment (ROI) of 106.30%. Total revenue rose 13.6 percent to $643.6 million, above the average analyst estimate of $627.4 million.
He added that North Korea would not rule out "the use of the most extreme measures in response".
North Korean leader Kim Jong Un gives field guidance at the Sci-Tech Complex, in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang October 28, 2015. It could also breach the latest United Nations sanctions barring the North's textile exports if the country seeks outbound shipments. A Chinese Foreign Ministry spokesperson expressed hope that the relevant countries "will not engage in words or deeds that provoke one another or raise tensions", while a Kremlin spokesperson stressed that [Moscow] has "demanded that the countries involved [in the North Korean nuclear issue] exercise restraint and avoid measures that exacerbate the situation".
"While I would not characterize them as the best in the world, they are among the best in the world and the best organized", Army Gen. Vincent Brooks, commander of U.S. Forces Korea, told the Senate a year ago.
Fears the crisis could spiral into open conflict have risen as the communist state demonstrated rapid progress in its efforts to develop a nuclear-tipped missile that could target the US mainland despite several rounds of punishing United Nations and other worldwide sanctions against it.
"Our country has been unsuccessfully dealing with North Korea for 25 years, giving billions of dollars & getting nothing".