Weapons grade uranium found again in Iran?

The U.N. nuclear watchdog has found traces of weapons-grade enriched uranium at a second site in Iran, diplomats said on Thursday, and President Bush warned Tehran it faces global condemnation.

One diplomat told Reuters the discovery could support Tehran's explanation that the discovery of highly enriched uranium at a previous site in Iran was due to contamination from imported components.

But several other diplomats said it could support the U.S. theory that Iran has been secretly purifying uranium for use in a nuclear explosive device -- a charge Tehran denies. . . .

What the discovery does support is that Iran has weapon grade uranium. The discover at a second site indicates that the discovery at the first site was not the result of some hard to believe accident. The claim that this supports "Tehran's explanation" just seems bizarre. How does the fact that this weapons grade uranium was found at a second site prove anything about imported components? Would finding such uranium at a third or fourth site make that case even stronger?