What did Trump say about Iran during his 9/11 Pentagon speech, and how did he link it to the broader war on terrorism?

Trump stated, 'It is a war on sick, horrible terror' and asserted that U.S. service members are working 'to ensure the world’s number one sponsor of terror, the Islamic Republic of Iran, will never ever have a nuclear weapon,' directly tying the ongoing Iran campaign to the post-9/11 fight against terrorism.

Why did Trump choose to speak at the Pentagon instead of the Ground Zero ceremony, according to the article?

According to the article, Trump said a 'strong request was made for me to be at the Pentagon,' and the New York Times reported—citing unnamed sources—that he opted not to attend the Ground Zero ceremony because he wanted to deliver a speech, though that event has long barred political speeches to keep focus on victims and families.