The warning was delivered ahead of his visit to Japan and South Korea. However, he is optimistic that the NATO military alliance has the ability to respond to any threats, including Pyongyang missiles.
"We recognize that Europe has also entered missile range (North Korea), and NATO member countries are in danger," Stoltenberg told the Yomiuri Shimbun newspaper on Sunday.
"NATO has protected its member states from the threat of ballistic missiles through prevention, but diplomatic efforts are needed to find a peaceful solution to the conflict," he said.
"NATO has the ability and determination to respond to any threats and aggressors," Stoltenberg said in a separate interview with Jiji Press. "There are no NATO allies and of course NATO does not want war. It will be a disaster. "
The North Atlantic Treaty Leader will visit Japan on Monday (30/10/2017) and Tuesday tomorrow where he will meet with Japanese Prime Minister Shinzo Abe and Defense Minister Itsunori Onodera. The NATO chief will also visit the Japanese naval base at Yokosuka before traveling to South Korea.
The military alliance is not directly involved in efforts to resolve the ongoing North Korean crisis, but fully supports its allies in the region, and the United States has pledged to protect its allies.
US Defense Secretary James Mattis, during a visit to South Korea on Saturday, has been firm about his response to the threat of Pyongyang's attack.
"Make no mistake, an attack on the United States, or its allies, will be defeated. And the use of any nuclear weapon will be greeted with a great and effective huge military response, "Mattis said.
The CIA has warned that North Korea needs a few more months to be able to launch a nuclear strike into the US mainland. But, the government of President Donald Trump promised to prevent that from happening.