President Trump is questioning Iran's denial of involvement in the weekend attack on Saudi Arabia's biggest oil refinery. Trump tweeted that Iran has a history of lying. He added, "We'll see?" That followed an earlier Trump tweet that the U.S. is "locked and loaded" on a possible response to the attack. He said it is dependent on verification and noted that the U.S. is waiting to hear from the Saudis. Trump also tamped down concerns about a spike in global oil prices, saying the U.S. has plenty of oil.