Theresa May to write letters of last resort for Trident subs

Letters of last resort written by Theresa May will contain orders on what Trident submarines are to do if a nuclear strike has destroyed the United Kingdom.

Theresa May is the new Conservative Party leader and will become the UK’s second female prime minister today, taking charge at one of the most turbulent times in recent political history.

The letters of last resort are stored inside two safes in the control room of each submarine. The letters are destroyed unopened after a Prime Minister leaves office, so their content remains known to only them.

The United Kingdom relies on four Vanguard-class submarines to provide its nuclear deterrent. At least one submarine is always armed and on active service, carrying 16 Trident II submarine-launched ballistic missiles each with a range of 7000 miles, and 12 independently controlled warheads each capable of destroying a large city.

According to the December 2008 BBC Radio 4 documentary The Human Button, there were four known options given to the Prime Minister to include in the letters of last resort. The Prime Minister instructs the submarine commander to:

• retaliate with nuclear weapons;
• not retaliate;
• use his own judgement; or
• place the submarine under an allied country’s command, if possible. The documentary mentions Australia and the United States.

Former chief of defence staff Lord Guthrie said that Tony Blair “went quiet” when he had to write the letters.

In a BBC Radio 4 documentary, Lord Guthrie said:

“I think quite honestly, like most prime ministers, he hadn’t given a huge amount of thought to what this really meant. And it is actually an awesome responsibility.

It really comes home to you that he could, if the circumstances demanded it, create devastation on a huge scale.”

Writing the letters is one of a number of protocols that May will likely complete today.