The UK will test its emergency war alert system for the first time in two years, as the government warns citizens to prepare for war.

All UK devices will blast out an alarm tone later this year in a new test of the ‘Emergency Alert System’.

The UK emergency war alert, first launched in 2023, is designed to warn the public of a potential danger to life nearby.

This latest test comes as the government’s security strategy warns that the UK homeland could come under ‘direct threat’ in a ‘wartime scenario’.

The renewed testing of the UK emergency war alert system also comes at a time when escalating conflict in the Middle East has sparked concerns of a wider war between nuclear powers.

In early June 2025, the UK Prime Minister, Keir Starmer, unveiled a Strategic Defence Review (SDR).

The UK war alert entails the most serious threats since the Cold War, including Russian aggression, cyber?attacks, and threats from Iran, North Korea, and China.

Here are six key things to know about the UK emergency war alert:

What a ‘War Alert’ Means

Immediate action required: If the alert sounds, phones will lock briefly, forcing acknowledgement before use. The message will deliver clear instructions, ranging from immediate sheltering to evacuation or avoiding disruptions.

Psychological readiness: This system aims to ensure people can act rapidly during critical emergencies, bridging the gap before traditional sirens or TV/radio alerts kick in.

New Public Emergency Alert System

Mobile “war alert” sirens: All compatible UK mobile phones will receive loud, siren-like alerts (10 seconds long) via cell broadcast—to warn about imminent threats like attacks or large-scale emergencies.

System history: Launched in 2023, the system is being tested regularly, both April and upcoming nationwide tests have caused public attention for their loudness.

Usage scenarios: While it covers severe weather, terror threats, or flooding, it’s now positioned to respond in a wartime scenario, clearly marking a shift from its primary civil?emergency role.

Terrorist threat levels

MI5 and the Home Office maintain a five-tier scale: low, moderate, substantial, severe, critical.

As of June 2025, the national level remains substantial, meaning a terrorist attack is likely, but not imminent.

The concern In the UK is due to global tensions, particularly Russia and Iran, plus a rise in cyber and hybrid threats targeting national infrastructure.

Heightened national security posture

The June 2025 National Security Strategy emphasises defence readiness: plus defence spending aim of 5 % GDP by 2035, large-scale drills (“Pegasus”), annual crisis exercises, and nuclear-capable F?35 deployment.

Scenarios now include missile strikes, cyberattacks, and threats on UK soil.

Local emergency coordination and community impact

Residents around Aldermaston, near a nuclear warhead facility, face periodic sirens and alerts, managed via a community?text alert system for incidents at the Atomic Weapons Establishment.

The Church of England Is also preparing to support spiritual and community resilience during a crisis.

Public action and advice

Stay aware: Check if your phone is compatible—most modern 4G/5G devices are.

Prepare: Keep an emergency kit (basics like water, meds, documents) accessible, especially with a system now ready to trigger during war-like scenarios.

Keep calm: Sirens are loud by design, but alerts are meant to be informative. (Saturday Tribune)