Iran can dig deeper and put targets around civilians, but there's another way to avoid our strikes, too--put them in other countries.
Already, we've seen Iran's hand in North Korea and Syria. Let's add Venezuela to the list of countries that could do nuclear work for Iran, making any strike on Iran less than complete:
Venezuela President Hugo Chavez said the South American country plans to develop a nuclear energy program with Russia and doesn’t want to build an atomic bomb.
Just like Venezuela is helping Iran avoid sanctions on gasoline sales to Iran, Venezuela will help Iran with its nuclear program.