A military veteran and rising GOP senator vouches for Donald Trump as commander-in-chief

CLEVELAND - Iowa Sen. Joni Ernst, a veteran of the Iraq War who was once thought to be on Donald Trump's shortlist for vice president, told reporters on Monday that she's confident the presumptive Republican presidential nominee would make a good commander-in-chief.

Foreign policy experts - some from within the Republican Party itself - have been critical of Trump's positions and said he would not be a suitable commander-in-chief.

Ernst explained why she disagrees.

"I think he will be a very good commander-in-chief and I witnessed that when I was visiting with him one-on-one," she said in response to a question from Business Insider.

"He was very, very attentive to what I had to say about national security issues, he is concerned about our allies and making sure that they're stepping up to the plate as well, which is really good, and I think he understands that we need to strengthen our military. He's made those statements."

Trump has called NATO "obsolete" and insisted that member countries contribute more to their own defense.

Ernst implied that Hillary Clinton, the presumptive Democratic nominee for president, wouldn't insist on these necessary changes.

"We don't see that coming from the Hillary Clinton presidency," Ernst said. "It's more of the same old tired policies that don't actually address the issues. They may dance around some other fancy topic, but they're not getting to the root of the problem, and it is Islamic terrorism."

Ernst spoke to reporters after an event for Ohio Sen. Rob Portman, who is up for reelection this November. Ernst is in Cleveland this week for the Republican National Convention and is expected to deliver a speech Monday night focusing on national security.