U.S.-U.K. Celebrate 60 Years of Mutual Defense Agreement. What Is It?

By Katie Lange
Defense Media Activity

July 3 marks the 60th anniversary of the mutual defense agreement between the United States and the United Kingdom, and it’s just as important now as it was at the start of the Cold War.

Marine Corps photo by Sgt. Jeffrey Anderson

So what is the U.S.-U.K. MDA?

The agreement, made in 1958, gave our countries the opportunity to exchange defense information relevant to nuclear weapons, naval nuclear propulsion and nuclear threat detection. In other words, it’s all about working together on nuclear deterrence and advancing our separate nuclear weapons programs.

In the current global climate, where security challenges and threats of nuclear terrorism and proliferation are common, that’s key.

Why Make This Pact?

The U.S. has nuclear agreements with other countries, including France, but this is considered the most comprehensive.

The U.S. and U.K. have always shared a special relationship, and our nuclear defenses are no exception. In the 1940s, during World War II, British scientists identified the means to make an atomic explosion in a device that could fit onto an aircraft. They shared that information with the U.S., which led to our pursuit of the Manhattan Project – the creation of the first atomic bomb – and the nuclear age.

About 15 years later, Britain successfully tested the hydrogen bomb, and the Soviets kicked the Cold War into high gear, launching Sputnik and triggering the great “space race.”

Since the U.S. and Britain shared the same nuclear security goals and were both wary of the Soviets, our nations decided to partner up, and the mutual defense agreement was born.

What Does It Do?

The MDA allows us to exchange technology, equipment, information, and even nuclear materials such as plutonium or highly enriched uranium. Our countries cooperate on defense planning, training, delivery systems and even on some intelligence. The agreement gives us a chance to work together on nonproliferation research, which lets us better understand the safety, security and reliability of each country’s nuclear weapon stockpiles.

“The U.S. is one of our closest allies, and we hope to share another 60 years of defending peace and stability throughout the world during such uncertain times,” said U.K. Defense Ministry Permanent Secretary Stephen Lovegrove during a 60th anniversary celebration at the U.S. Department of Energy.

In the past several decades, the agreement has ensured our nuclear capabilities and propulsion plants are safe, reliable and effective. It’s also been essential to counterterrorism efforts and has helped our countries design nuclear reactors for our naval fleets.

Who Decides What Is Shared?

In the U.S., the DoD and DoE are responsible for controlling the dissemination of U.S. atomic information. The secretary of defense and the chairman of the Atomic Energy Commission authorize MDA exchanges.

Key aspects of the agreement have been renewed and amended every 10 years. The latest amendments came in December 2014 and extend the agreement to 2024.

READ MORE: National Nuclear Security Administration

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U.S.-U.K. Celebrate 60 Years of Mutual Defense Agreement. What Is It?