China's recent test of an anti-satellite weapon that pulverised an old weather satellite was a big mistake. The move makes a mockery of China's long-standing opposition to such capabilities in the hands of other powers. More significantly, it threatens to undermine an uneasy moratorium on the development of space weapons that has largely endured since the end of the cold war.
Worrying though this is, the US must not overreact. Rushing into a space weapons competition would not serve American strategic interests. But neither are sweeping controls on the military uses of space plausible or desirable. To develop an effective space policy, the US and its allies must bear several principles and realities in mind.
First, the US increasingly uses space for military purposes, particularly for tactical war-fighting. Real-time data links and GPS-guided bombs are only the latest manifestations of this trend. The dependence on reconnaissance, targeting and communications satellites will surely grow.
Second, although the US in particular has militarised space in such ways, space has yet to be weaponised. That is, hardly any weapons have been put into orbit or deployed to attack satellites. The Chinese test works against this generalisation, of course, but does not yet repudiate it.
Third, those countries that rely on space systems cannot expect them to remain almost invulnerable. The nuclear powers already have ballistic missiles that have latent anti-satellite capabilities. The US, in particular, is also pursuing several ballistic missile defence programmes that also could be modified for anti-satellite weapon purposes; other countries may soon have similar, if less technically advanced, capabilities. For US armed forces, inherent vulnerabilities in low-altitude imaging satellites are of particular concern. They could be attacked by the type of weapon China has just tested, or microsatellites or lasers.
While regrettable, the Chinese anti-satellite test is a partially understandable step by a rising military power. China's test was more blatant than America's ongoing efforts in space but, if one can forgive the pun, it has not occurred in a vacuum.
Fourth, other countries will gradually become more able to use space for offensive military purposes. In particular, they are likely to gain the capacity to find and target large mobile assets such as ships and big formations of ground forces.
Basic technological and strategic realities support the argument for a moderate and flexible US military space policy. These realities also refute the extreme positions that have been espoused by prominent US policymakers in recent years. The late 1990s report of the Commission on Outer Space, for instance, warned of a possible space "Pearl Harbor". It implied that the US needed rapidly to take many steps - including offensive ones - to address such a purportedly imminent threat.
Most US satellites are not vulnerable to attack today nor are they likely to be in the years ahead. Thereafter, threats may often be handled through relatively passive measures and through redundant systems rather than an all-out space weapons competition. The Chinese anti-satellite test does put lower-altitude reconnaissance systems in greater jeopardy, but not higher-altitude communications and targeting satellites.
By racing to develop its own space weapons, the US would cause two unfortunate consequences. Militarily, it would legitimate a faster space arms race than is otherwise likely - something that can only hurt a country that nearly monopolises military space activities today.
Second, it would reinforce the current prevalent image of a unilateralist US, impervious to the stated will of other countries (as reflected in the huge majority votes at the United Nations in favour of negotiating bans on space weaponry).
For all its popularity, a wide-ranging ban on space weaponry is unjustified. Such an accord would be generally unverifiable and unable to reverse the simple fact that many ballistic missile defence systems can be transformed into anti-satellite weapons with relatively modest adjustments.
So the right policy for the US in space remains hedging and going slow. Extreme solutions can be more rhetorically appealing. But they fail to address the technical and strategic realities of the day and should not be adopted. That said, a few more such Chinese tests and we may have little choice.