It has become increasingly clear that Iran is making rapid progress toward attaining a nuclear weapons capability as U.S. officials have confirmed the presence of various nuclear sites that Tehran has failed to disclose
Undisclosed nuclear weapons sites were discovered in Iran.
Actually, the US confirmed the presence of 'various nuclear sites' that Tehran has failed to disclose - it does not say they were weapons facilities.
( z1 discover :ARG1 ( z2 site :location-of ( z3 weapon :mod ( z4 nucleus ) ) :ARG1-of ( z5 close :polarity - ) ) :location ( z6 country :name ( z7 name :op "Iran" ) ) )