The exercise allows USA and RoK forces to train together to deter aggression, preserve the armistice, and defeat any attack against the alliance.
The Vigilant Ace exercise, which was scheduled before the missile launch, involves 230 aircraft and about 12,000 service members from the USA and South Korea.
China has condemned North Korean nuclear tests and gradually distanced themselves from their once-close ally, even backing United Nations sanctions against the fellow socialist country in September following a test of their nuclear program.
The sheer size of the US-South Korea exercise, as well as the continuous American military buildup in the peninsula since the spring, may be taken by Beijing as indication that the US plans to do exactly that.
On Monday, the People's Liberation Army Air Force (PLAAF) flew exercises in "routes and areas it has never flown before" over both the Yellow Sea that divides China and the Korean Peninsula as well as the East China Sea between China, South Korea, Japan, and Taiwan.
"If necessary, the president and the United States will have to take care of it, because he has said he's not going to allow this murderous, rogue regime to threaten the United States with the-with the most-destructive weapons on the planet".
This handout taken and released by the South Korean Defence Ministry in Seoul on December 6, 2017 shows a US Air Force B-1B Lancer bomber, two US F-35A and two US F-35B stealth jets flying over South Korea with South Korea's two F-16 and two F-15K fighter jets during a joint military drill.
Clashes continue as Israel strikes Gaza militant posts after rockets fired
The launches set off incoming rocket alert sirens shortly after 6 p.m., in the Hof Ashkelon and Sha'ar Hanegev regions, northeast of the Gaza Strip.
North Korean Vice Foreign Minister Pak Myong Guk met Feltman on Wednesday in the North Korean capital, Pyongyang, and discussed bilateral cooperation and other issues of mutual interest, KCNA said. The State Department said on Tuesday he was not carrying any message from Washington.
The joint exercise is created to enhance readiness and operational capability and to ensure peace and security on the Korean peninsula, the US military had said before the drills began. North Korea's increasing nuclear and missile capability would top the agenda, it said.
North Korean state media - which describes the B-1B Lancer as a nuclear strategic bomber - denounced the exercise over the weekend.
The danger, because of the bellicose statements emanating from the White House, is that North Korea could easily mistake an exercise as a prelude to an actual attack.
The military exercises, called "Vigilant Ace", are created to enhance joint readiness and operational capability of US extended deterrence, South Korea's Joint Chiefs of Staff said in a statement. China is North Korea's lone major ally and fears widespread instability on its border.
Image of North Korea's latest test launch of an intercontinental ballistic missile or ICBM.
Russia has communication channels open with North Korea and Moscow is ready to exert its influence on Pyongyang, RIA news agency quoted Russian Deputy Foreign Minister Igor Morgulov as saying on Tuesday. The United States, which has 28,500 troops stationed in South Korea, a legacy of the 1950-53 Korean War, denies any such intention.