An ominous email addressed to students at the University Of Hawaii on Monday probably caused most of them to do a double-take. The subject line warned students of what they should do should North Korea follow through on its threats to launch a nuclear attack on the islands.

Titled with the scary words “in the event of a nuclear attack,” the email recalled the Cold War era of the 1950s, as it warned the students to listen to instructions to shelter in place.

Missile tests by North Korea raise alarm

According to a report by Hawaii News Now, while the subject line of the emails was enough to terrify anyone, the content did mention that a nuclear attack was an “unlikely event.” However, it mentioned concerns over the current missile tests being launched by Kim Jong-Un in North Korea.

It went on to say state and federal agencies are currently providing information about potential nuclear threats and advising what to do should a nuclear attack and resulting radiation emergency occurs. Students and faculty were told to be aware of the emergency sirens and the importance of following instructions to “shelter in place.”

Not the first warning in Hawaii about possible nuclear attack

As reported by the New York Daily News, this isn’t the first notification relating to the possibility of a nuclear attack in Hawaii, as information was disseminated to residents this summer, following North Korea’s test of a missile they say could reach the Hawaiian Islands.

According to experts, the country is making progress with the miniaturization of a nuclear warhead which they believe could be fitted on an intercontinental ballistic missile which would take some 20 minutes to reach the Aloha state. There have also reportedly been missile defense tests run by the U.S. military off the coast of Hawaii and also on the West Coast in the U.S.

The ominous emails were sent due to rising tensions between the U.S. and North Korea, with President Donald Trump announcing that diplomatic efforts with “little Rocket Man” – his Twitter nickname for Kim – have stalled.

While international efforts have been launched to try and find a peaceful solution between the two countries, both Trump and Kim have recently been involved in insult-swapping, with Trump threatening the Asian nation with “fire and fury.” Kim’s response was to warn that North Korea’s weapons of mass destruction form a strong deterrent against a strike by the U.S.

According to a report by the Yonhap News Agency, Trump is due to visit various Asian countries in early November, including North Korea’s southern neighbor, South Korea. That report states that there is a possibility of the U.S. president visiting the Demilitarized Zone between the two countries during his visit.