( Continue from "Chronology, 1958") It was the Soviet Union who finally resolved the question. In March 1959, SS-6 testing resumed, but with an important difference. In stead of the irregular research and development launches of 1957-1958, the new series followed a regular four-per-month pattern, indicating that the SS-6 was in the final stages of the test program. It would be only a matter of time before deployment began. By the end of 1959, U.S. estimates indicated that the Soviet Union might have ten missiles ready for launch. Accordingly, attention shifted in 1959-1960 to finding out the actual number of Soviet ICBMs rather than pursuing the more hypothetical estimates of future production. The U-2 went hunting ICBMs. In addition to photographing suspected ICBM sites, they were also covering the Soviet railway system. The SS-6, with its four strap-on boosters, was simply too large to be moved by road (typically dirt and virtually impassable in bad weather). The stage sections would have to be brought to the launch site by rail. The U-2 photographs should show the stages in the process of moving from the factories to the launch sites. Even if neither was actually located, these missiles, caught in transit, would indicate the level of deployment. There was only one problem-the U-2s weren't finding any missiles: no ICBM sites were confirmed; no missiles were seen on the railroads. Interpretation of this seeming lack of evidence spanned the complete range of possibilities.

The Air Force yielded its position only slightly: they thought that the start of the Soviet missile buildup had been pushed back 6 months, but they stayed with their earlier high production rate estimate. The Air Force numbers were now 100 ICBMs in 1960, 500 by 1961, 1,000 by 1962, and a total of 1,500 by 1963. At the other end of the estimate spectrum was Army and Navy intelligence. They believed that no large-scale deployment was in fact underway or even planned. They pointed to the numerous test failures of the SS-6. Of the fewer than twenty launches made between March 1959 and January 1960, less than half had made it to the target area. Also, Army and Navy intelligence noted the comparatively short range of the SS-6-only about 3,500 nautical miles (6,482 kilometers). Others argued that this was the maximum distance the Soviet Union could monitor the tests. In the Army and Navy's opinion, the lack of evidence meant a lack of missiles.

The CIA adopted a middle position. It offered two projections;  the first was based on an "orderly" program. It assumed a production rate of 3 missiles per month, eventually working up to 15 per month, which would give the Soviet Union 36 ICBMs by the end of 1960 and about 400 by 1963. The CIA's other projection envisioned a crash program with production starting at 15 ICBMs per month. In this case, the Soviet Union would have 140 to 200 missiles by mid-1961 and 500 by 1963. (The variation is due to when production actually began.) In late 1959 to early 1960, the CIA concluded that the orderly program was the most probable, since a crash effort could not escape the notice of the U-2. The CIA acknowledged that the Army and Navy were correct about the SS-6's high failure rate. But the CIA noted that this was to be expected with the new technology. (Of the first thirty- five Atlases launched, seventeen were failures.)