The US government will no longer conduct tests of anti-satellite weaponry that could create debris clouds in orbit.

Vice President Kamala Harris announced this week that the United States will ban direct-ascent anti-satellite (ASAT) missile tests that create orbital debris.

“These tests are dangerous and we will not conduct them,” Harris said in a speech at Vandenberg Space Force Base in California.

The self-imposed US ban on destructive anti-satellite weapons tests is an effort to start an international push to develop “new norms for responsible behavior in space,” she said, calling on other nations to do the same.

“Without clear norms we face unnecessary risk in space,” she said. “Through this new commitment and other actions, the United States will demonstrate how space activities can be conducted in a responsible, peaceful, and sustainable manner.”

ASAT weapons – usually customized missiles launched from the ground or high altitudes via planes – can create huge debris clouds when tested on in-orbit machinery. Even a small piece of debris traveling at thousands of miles per hour in orbit can damage or potentially destroy other satellites. Most tracking is limited to pieces larger than 1cm, leading to an increasing number of avoidance manoeuvrers as more satellites are being launched.

A destroyed satellite can cause a cascade; each trackable piece of debris can potentially destroy another satellite, which in turn can create more debris that can destroy other satellites. Kessler Syndrome warns of a scenario where an excess of space debris begins to collide uncontrollably with satellites, causing an unstoppable cascade of collisions and debris that could render orbits unusable by satellites or manned missions for generations.

The Secure World Foundation (SWF) estimates there have been around 16 debris-creating ASAT weapons tests in history. Five have occurred since the turn of the millennium; China’s 2007 remains the most damaging in terms of debris pieces created, with more than 3,500 pieces tracked at the time and at least 2,000 still in orbit.

The most recent ASAT test was conducted by Russia last year; the defunct Cosmos-1408 spy satellite was destroyed with a missile, creating a large debris cloud of more than 1,000 pieces. The move drew sharp rebuke from US officials and created tens of thousands of conjunction alerts with other satellites.

The US has long been one of the leading developers of space-centric weaponry, conducting the first ASAT tests in the late 1950s. The US has conducted at least three ASAT tests that have created debris; two in the mid-1980s and one in 2008.

The US Navy destroyed the malfunctioning US spy satellite USA-193 from a decaying orbit using a modified RIM-161 Standard Missile 3 fired from a warship in the Pacific. The satellite was officially destroyed due to the presence of hydrazine and beryllium on board and the potentially hazardous effect the chemicals could have if they leaked over a populated region.

“With this policy, the US is demonstrating leadership at the international level,” the SWF said in a statement. “By adopting this policy unilaterally, the US is signaling that it sees this behavior as being so irresponsible that it is unwilling to engage in it. As productive discussions in multilateral fora continue on norms and principles for responsible behavior in space, this new US policy sends a clear message about US commitment to ensuring the long-term sustainability of outer space.”

“I’m really excited about this announcement because it’s not just the US committing to refrain from these behaviors, it’s about trying to establish international norms for responsible behavior in space and really encouraging other countries to join in,” Robin Dickey, space policy expert at the Aerospace Corp., told SpaceNews.

The announcement drew criticism from Republican leaders. Colorado’s Rep. Doug Lamborn, the top Republican House Armed Services Committee’s subcommittee on strategic forces, called the decision to stop ASAT missile tests “a unilateral, voluntary, and completely unnecessary commitment.”

“This decision creates more opportunities for China and Russia to hold our assets in space at risk while they continue to field ASAT technologies and create hazardous space debris,” Lamborn said in a statement. “An American commitment to not conduct ASAT tests creates a false equivalence between our carefully calibrated behavior in space and the reckless actions of China and Russia.”