The United States on Tuesday announced a successful test of its Terminal High Altitude Area Defense (THAAD) anti-missile system against an intermediate-range ballistic missile (IRBM) over the Pacific Ocean in a demonstration likely aimed at reassuring Asian allies nervous about surging tensions with North Korea.

The test, which media reports had characterized as the first use of THAAD to defend against a simulated IRBM attack, came just a week after North Korea said it had launched a long-range missile that experts said is capable of striking parts of Alaska.

Until Tuesday's test, THAAD had been unproven against IRBMs, missiles that have a range of 3,000 to 5,500 km (1,800 to 3,100 miles).