As a candidate, President-elect Donald Trump said his "No. 1 priority" was to dismantle the "disastrous" nuclear deal with Iran. Tempting as that may be, Trump should resist. Instead, the man who fancies himself the world's greatest negotiator should use U.S. leverage to hold Iran to the letter of the agreement.
This is the hard work of diplomacy, which takes place mostly out of public view and off Twitter. At least Trump's job will be made easier by Congress, which just extended the Iran Sanctions Act, allowing the U.S. to punish Iranian entities involved with terrorism, illegal weapons and human-rights violations. Trump can and should also end the de facto policy of looking the other way at Iran's early infringements of the pact, such as the recent revelation that it had exceeded the deal's cap on how much heavy water it is allowed to stockpile.