Two more Patriot batteries and a THAAD missile defense system will be prepared to go later if needed, and the deployment will involve about 200 troops.

Military commanders and defense leaders have been working since last week to iron out what military aid to send to the region in response to what U.S. officials say was a brazen and unprecedented cruise missile and drone attack by Iran on Saudi oil facilities on Sept. 14.

President Donald Trump during a White House meeting last Friday put off, at least for now, any immediate military strike on Iran, but approved a broader effort to beef up security in Saudi Arabia and the region. He told reporters that showing restraint "shows far more strength" than launching retaliatory strikes now.