If you're referring to they as the Israelis, then your statement is not correct.
Various intelligence services said the same thing, and Colin Powell said this about the tubes we had in our possession and knew quite a bit about:
By now, just about everyone has heard of these tubes, and we all know that there are differences of opinion. There is controversy about what these tubes are for. Most U.S. experts think they are intended to serve as rotors in centrifuges used to enrich uranium. Other experts, and the Iraqis themselves, argue that they are really to produce the rocket bodies for a conventional weapon, a multiple rocket launcher. Let me tell you what is not controversial about these tubes. First, all the experts who have analyzed the tubes in our possession agree that they can be adapted for centrifuge use. Second, Iraq had no business buying them for any purpose. They are banned for Iraq. I am no expert on centrifuge tubes, but just as an old Army trooper, I can tell you a couple of things: First, it strikes me as quite odd that these tubes are manufactured to a tolerance that far exceeds U.S. requirements for comparable rockets. Maybe Iraqis just manufacture their conventional weapons to a higher standard than we do, but I don't think so. Second, we actually have examined tubes from several different batches that were seized clandestinely before they reached Baghdad. What we notice in these different batches is a progression to higher and higher levels of specification, including, in the latest batch, an anodized coating on extremely smooth inner and outer surfaces. Why would they continue refining the specifications, go to all that trouble for something that, if it was a rocket, would soon be blown into shrapnel when it went off?
The Israelis were pushing the tube issue before we were. We bought into a load of crap.
You contend "Most U.S. experts think they are intended to serve as rotors in centrifuges used to enrich uranium." Link? I'm sure you are well aware that the DEPARTMENT OF ENERGY did not agree with this assessment. Neither did various other intel groups, including the ones at State that, in hindsight, seemed to be the most accurate pre-war. What I stated is that no one who builds centrifuges has agreed that these tubes are designed for that purpose. If you want to controvert that, show me such a statement from someone who builds centrifuges.
And you are going to rely upon comments straight out of the Powell speech that he is running away from at top speed? Why don't you even acknowledge what our own DOE said about the tubes?:
"Based on the reported specifications, the tubes could be used to manufacture gas centrifuge rotor cylinders for uranium enrichment. However, our analysis indicates that the specified tube diameter, which is half that of the centrifuge machine Iraq successfully tested in 1990, is only marginally large enough for practical centrifuge applications, and other specifications are not consistent with a gas centrifuge end use. Moreover, the quantity being sought suggests preparations for large-scale production of centrifuge machines, for which we have not seen related procurement efforts - and the tubes’ specifications suggest a centrifuge design quite different from any Iraq is known to have. Thus, we assess that this procurement activity more likely supports a different application. ... While the gas centrifuge application cannot be ruled out, we assess that the procurement activity more likely supports a different application, such as conventional ordnance production. For example, the tube specifications and quantity appear to be generally consistent with their use as launch tubes for man-held anti-armor rockets or as tactical rocket casings. Also, the manner in which the procurement is being handled (multiple procurement agents, quotes obtained from multiple suppliers in diverse locations, and price haggling) seems to better match our expectations for a conventional Iraqi military buy than a major purchase for a clandestine weapons-of-mass destruction program."
There's your "US experts."
If you want to disagree with every rational post-war assessment of these tubes, that's fine. That's not the point at hand. The point at hand is that the Israelis saying they have "concerns" based on their intel is a far, far cry from "proof" that those concerns are actually fact.