SEOUL—North Korea showed off what appeared to be at least one new long-range missile at a military parade Saturday, as tensions simmer over the possibility of a military confrontation between the U.S. and North Korea.

The weaponry on show, which appeared to include a newly-modified intercontinental ballistic missile and two types of large launchers with never-before-seen missile canisters, is likely to trigger fresh concerns about the speed with which Pyongyang’s missile program has advanced in recent years.

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