A nuclear weapon detonated in the atmosphere can disable many satellites. The United States learned this in 1962, when a particularly powerful U.S. nuclear test victimized one British, one Soviet, and four U.S. satellites. The most famous casualty of this test was Telstar, a satellite than allowed the first transmission of television images across the Atlantic. Telstar inspired an instrumental record that topped the charts as its namesake was dying from nuclear weapon effects.

There have been very few tests of missiles used to blow up satellites. One was in 1985, by the Reagan administration. The impact of this test produced approximately 300 pieces of debris large enough to track, one of which came within one mile of crashing into the newly-launched International Space Station -- fourteen years later. China created to worst-ever man-made debris field by carrying out an anti-satellite test in 2007. The massive debris field generated by this test has endangered over 400 satellites.
There are now over 20,000 pieces of space debris large enough to track, and a great many more that escape detection. Debris endangers human spaceflight no less than satellites. The windows of the U.S. shuttle fleet needed to be changed over 70 times because of tiny debris hits. The International Space Station has dodged lethal debris over a dozen times. In low earth orbit, debris travels at approximately ten times the speed of a rifle bullet. A piece of debris the size of a child’s marble could strike a satellite with the same energy as a one-ton safe dropped from a five story building. Debris hits have pin-ball effects, creating new, mutating debris clouds. These debris clouds can make crowded space corridors unusable.
Some assume that a war in space will occur, so they seek superior war-fighting capabilities in this domain. The George W. Bush Administration endorsed this strategy, rejecting any diplomatic initiatives that might impair U.S. freedom of military action in space. The Pentagon demonstrated anti-satellite capabilities in 2008 by using a missile to destroy a malfunctioning intelligence satellite.
The Bush Administration’s approach was unsuccessful.  The debris problem rose to new heights because of the Chinese anti-satellite test, a collision between a functioning U.S. and a dead Russian satellite, and the break-up of orbiting Russian space junk. These events served to clarify that controlling and dominating a war in space will be as hard as controlling escalation in a nuclear war.

We have rules to promote highway safety and for air traffic, but very few rules apply to space. The Obama Administration and the European Union have endorsed a Code of Conduct to establish rules of the road for responsible space-faring nations. The most crucial norms in need of strengthening are debris mitigation, traffic management procedures to avoid collisions, and restraints on harmful, purposeful interference against satellites.
The practice of utilizing codes of conduct to set norms is not new. In 1972, the Nixon administration negotiated an “Incidents at Sea Agreement” with the Kremlin to help prevent dangerous games of chicken involving warships and submarines. In 1989, President George H.W. Bush negotiated a “Dangerous Military Practices Agreement” with Mikhail Gorbachev, establishing norms for ground and air forces operating in close proximity. The George W. Bush Administration agreed to two codes of conduct to help combat proliferation.
All of these useful diplomatic initiatives took the form of executive agreements, not treaties, because they didn’t control or reduce military forces. Space could also benefit from a code of conduct that clarifies wrongdoing, facilitates corrective responses, and reduces the likelihood of devastating accidents, miscalculations and collisions.
Krepon is the co-founder of the Stimson Center, a Washington-D.C.-based non-profit, non-partisan institution devoted to enhancing international peace and security.  Krepon has championed a code of conduct for space, which has now been endorsed by the Obama administration and the European Union. He also is the author of “Better Safe than Sorry: The Ironies of Living with the Bomb.”