At Paris in June 2009 and again at Zhuhai in November, the Chinese displayed drawings of a new SW-6 anti-radar unmanned aerial vehicle (UAV). It is characterized as a "radar-interfering UAV," which might mean either that it will simply jam a target radar, or that it could act as a decoy. It would be dropped by attack aircraft loitering near a strike group to jam its radars. Thanks to shrinking electronics, the SW-6 would weigh only 20 kg. No photographs were displayed, so presumably it is only in the design stage.
This is the latest move in the war of nerves the Chinese have been waging against the U.S. Navy and its carrier force, following the DF-21 missile with its maneuvering re-entry vehicle. Another is the characterization of the Chinese version of the Russian Su-27 as a Backfire equivalent, the implication being that the Chinese expect to fight their own version of the Norwegian Sea battle that the U.S. Navy expected to fight had the Cold War turned hot. SW-6 is presumably a powered version of defensive jammers such as the U.S.-Australian Nulka and the British Siren. It may also be related to the Israeli Harpy that the Chinese bought. This is an antiradar device that loiters until the target radar is switched on, then crashes into it. In the United States, the Naval Research Laboratory developed a series of electrically powered radar jammer/decoy airplanes (UAVs), but the shorter-endurance Nulka was adopted instead.
If SW-6 is more than vaporware, its announcement suggests that a new kind of lightweight jammer or lethal antiradar weapon is now becoming available. Current antiaircraft systems (and antiship missile seekers) generally employ monopulse fire-control radars, which are difficult to deceive. A large object such as a ship can produce complex signals that can throw off a single monopulse seeker (the technique is called cross-eye), but aircraft are too small to do so. Tightly coordinating multiple aircraft might solve the problem, but that drastically limits flexibility and may open the aircraft to attack by fighters.
As in the case of Nulka, a deceptive jammer (a blip enhancer, for example) might be an effective decoy against a monopulse radar because the radar will, its users hope, lock onto it instead of onto the real target (hence the importance of blip enhancement, to produce an overwhelmingly large radar target). The advantage of packaging the jammer in a UAV would presumably be that the aircraft could launch it from outside Fleet air defense range, before the airplane itself could be attacked. That seems an unrealistic hope, since systems like Aegis typically engage their targets tens of miles out, probably beyond SW-6 flight range (the Chinese drawing shows fighters dropping SW-6 UAVs within sight of a carrier).
The Chinese may imagine that they can deny Aegis the possibility of engaging at any range by surrounding incoming aircraft with decoys that they would keep replacing as the decoys fell behind the incoming aircraft. Again, that might be ineffective, particularly if the attackers faced multiple Aegis ships constantly combining their data by using the Cooperative Engagement Capability (CEC) and thus seeking to distinguish real from decoy aircraft. It is doubtful, for example, that SW-6 has anything remotely like the performance of a real Chinese attack aircraft.
Simple jamming seems unlikely because the small UAV probably has only limited reserves of jamming energy. It can certainly get much closer to a U.S. radar than a stand-off jamming aircraft, but in doing so it comes into the range of many more self-defense weapons, and its own jamming signal would probably make it a relatively easy target. It is unlikely that a single SW-6 can deal with the whole range of U.S. defensive radars, but its existence would make new infra-red search and track devices more valuable, as they would certainly lie outside its capability. Such sensors can be used for fire control (they are linked to laser rangefinders), hence would make it easier to shoot down the low-performance UAV, peeling it away from the airplane it was trying to cover. Moreover, current U.S. defensive missiles either act independently, without radar guidance or are commanded into position for terminal guidance (ESSM and Standard). Given linking technologies like CEC, the commands can probably be worked out despite the presence of some decoys. The commanding system can, moreover, have the missile approach its targets (say, airplane plus decoys) in such a way as to have a good chance of hitting the airplane rather than the decoy.
If future Chinese attack aircraft have reduced radar cross-sections, something like SW-6 might have so much more radar cross-section that it would be a reasonably effective decoy. Even then the attacker would have to overcome considerable obstacles. He could never be sure at what range to begin releasing decoys, and he could never be sure of whether he was already being tracked-CEC has shown considerable potential against stealthy targets. Releasing decoys too late would make it relatively easy to distinguish them from the real target.
This is not to dismiss UAV decoys altogether. The more like a bomber the decoy is, the better the chance that a mass of decoys will confuse air defenses. All air defense systems have their limits, although modern systems can track and engage many more targets than their predecessors. Computer air defense systems, beginning with the Semi-Automatic Ground Environment (SAGE) system used for North American air defense from the late 1950s on, were largely a way of overcoming saturation due both to target numbers and to target performance-the faster the targets, the less time the system had to react to them. Experiments immediately after World War II revealed the unpleasant truth that not only could systems (such as those based on ships' combat information centers) be saturated, but that their operators usually could not tell how badly that was happening.
The computers serving SAGE and the more capable ones serving the U.S. Navy's compact (and faster-running) Naval Tactical Data System could handle perhaps 128 or 256 targets at one time. Defenders knew that the Russians might drop decoys from their bombers (U.S. bombers were so equipped), but they felt confident that they could distinguish bomber from decoy, largely because they would track the bomber before it dropped its decoy. The main threat of the 1960s was that the Soviets might make ground-launched decoys that would look like bombers because they would come into view about when the bombers did, and because they would have bomber-like performance and radar cross-section. The U.S. Air Force developed exactly such a decoy (which it did not put into service), and there seemed no good reason why the Russians would not do the same thing. The main reason no Soviet decoy entered service was probably that, unknown to Americans, Soviet Premier Nikita Khrushchev rejected bombers in favor of missile-carrying aircraft, the assumption being that high missile performance would overcome air defenses.
When the Chinese talk about Su-27s as Backfire equivalents, they are saying much the same thing, but the missiles these aircraft currently carry (the Soviet AS-17/Kh-31) lack the range of the AS-4 the Backfire carried. It also likely lacks an important feature of the Soviet missile: a data link by means of which a Backfire below the horizon could fire a missile that could then be commanded to lock onto the target. An Su-27 or its Chinese equivalent probably has to get a lot closer to a U.S. carrier before attacking, and that offers the carrier's defending fighters valuable opportunities.
Weapons like SW-6 are pointless except in a strategic or tactical context. The weapon and the Chinese air attack on carriers might be significant either in an opening-of-war scenario or in an attack after hostilities had begun. In the former case, the carrier's air defenses normally might track the approaching Chinese aircraft, but almost certainly would not be allowed to fire first. In the latter case, the carrier would try to project defenses as far away as possible, in a revived version of the late Cold War Outer Air Battle, the attempt to "kill the archer rather than the arrow," to destroy the enemy anti-carrier aircraft before they could launch. As noted, this outer air battle would probably be somewhat easier to fight, but on the other hand an Su-27 is considerably more maneuverable than a Cold War Backfire.
The other scenario is more interesting. During the Cold War, the U.S. nightmare was a Soviet surprise attack. How could the Fleet defend itself, particularly if killing Soviet aircraft well short of missile launch range was the best defense? In one famous war game, the solution was to have the President warn on the Hot Line that any Soviet aircraft flying within 50 miles of the task group center had committed an act of war, but it seems unlikely that any real President would make that call. SW-6 in effect solves this problem for us, because a battle group commander could easily see SW-6 as a weapon fired by an approaching Chinese aircraft. That firing would trigger defensive measures, including attempts to shoot down the airplane which had launched the UAV even if it later turned out that SW-6 was not lethal in itself. There would be no way of being sure, and the Chinese do operate a lethal antiradar UAV, the Israeli Harpy.
So perhaps this particular move in the Taiwan Strait war of nerves is actually the opposite of a new effective means of carrier-killing: it is really an excellent way of unambiguously warning us that an anti-carrier attack is coming. That probably did not occur to its creators, and the further implication is that they and probably their sponsors have not yet spent much time thinking through the larger tactical questions of anti-carrier warfare.