North Korean leader Kim Jong-un's sister condemned the drills involving the United States, Japan and South Korea, in a report published on state media KCNA.
At least seven missiles flew to an altitude of 100km and covered a range of 400km before falling outside Japan's exclusive economic zone into the ocean, Japan's Defence Minister Gen Nakatani said.
They were fired on Tuesday morning from near Sariwon, North Hwanghae Province, South Korea's Joint Chiefs of Staff said.
The United States was consulting closely with South Korea, Japan and other regional allies after the launches, and continued to monitor the situation, the US military said.
The latest launch follows North Korea's test last week of a huge new solid-fuel intercontinental ballistic missile dubbed Hwasong-19, and comes hours before voting opens in the US presidential election.
"If the ICBM was meant for the US, the latest ballistic missiles are for South Korea," said Yang Moo-jin, president of the University of North Korean Studies in Seoul.
Pyongyang's launch came after Vladimir Put met North Korea's foreign minister at the Kremlin. (EPA PHOTO)
"Directly, it is to protest the joint air drills by South Korea, US and Japan. Indirectly, it is to show off their presence last minute before the US presidential election," said Yang, who also saw the intent as to deflect the international community's attention away from criticising the dispatch of North Korean troops to Russia.
North Korean state media KCNA on Tuesday said Kim Yo-jong, the powerful sister of the country's leader, Kim Jong-un, condemned the recent military drills by the United States, Japan and South Korea as threats and said they justified North Korea's nuclear reinforcement.
The missile launch also came after Russian President Vladimir Putin unexpectedly met North Korea's foreign minister Choe Son-hui on Monday.
During Putin's surprise meeting in the Kremlin with Choe, the pair shook hands for a full minute at a time of mounting concern in the West that North Korean soldiers are about to enter the Ukraine war on Moscow's side.
On Monday, the US also called out Russia and China at the UN Security Council for "shamelessly protecting" and emboldening North Korea to further violate UN sanctions by advancing its ballistic missile, nuclear, and weapons of mass destruction programs.
South Korean Defence Minister Kim Yong-hyun noted in October that North Korea "would want to exaggerate their existence around the season of the US presidential election before and after the election" by show of force such as an intercontinental missile test or another nuclear test.
