Prime Minister Benyamin Netanyahu of Israel used one of the most prominent platforms in the world on Tuesday to warn against what he called a “bad deal” being negotiated with Iran to freeze its nuclear program, culminating a drama that has roiled Israeli-American relations for weeks. In an implicit challenge to President Obama, Mr. Netanyahu told a joint meeting of Congress that Iran’s “tentacles of terror” were already clutching Israel and that failing to stop Tehran from obtaining nuclear weapons “could well threaten the survival of my country.” The deal Mr. Obama seeks will not prevent a nuclear-armed Iran, he said, but “will all but guarantee” it.