The Answer is No.

The Proliferation Security Initiative: Can Interdiction Stop Proliferation?

What PSI cannot be viewed as is a substitute for these other elements of a nonproliferation policy. No interdiction effort can be 100 percent effective. Intelligence will not always be accurate, ships may only dock in ports of states that do not subscribe to the initiative, and the indigenous capability to produce WMD components without foreign assistance is rapidly spreading.

Correct, but the but the advantage of the PSI is that it makes operations harder for the bad guys and so makes it more likely that they'll trip up.

-HJC