Sen. Rand Paul (R-KY) joined Martha MacCallum this morning to react to Hillary Clinton's appearance in Iowa and the latest beheading of a Western journalist by ISIS.

Paul said he is looking to decide in the spring about a presidential bid. Paul said he still wants to see the former secretary of state back in Washington answering questions about the Benghazi attack, specifically the issue of what the CIA annex in Benghazi was being used for.

"I asked her point blank last time: 'what were they doing in the CIA annex and did that have anything to do with the attacks?' And she acted as if she knew nothing about it. But it's funny, now reports have been coming out for about a year saying that she was the biggest and most eager to get arms out of Libya and send them into Syria," said Paul.

Martha pointed out a Washington Post piece that questioned whether he has been shifting his positions on some issues ahead of a possible presidential run.

She recalled that a few months ago, Paul was not convinced that there was American interests at stake against ISIS in Iraq and Syria.

Paul responded that he has never wavered on his stance that there should always be a vote in Congress if America goes to war. Paul disagreed with Sen. Lindsey Graham's contention that U.S. ground troops will be needed to defeat ISIS.

He argued that the first 10,000 troops into battle should be from Iraq and the next 10,000 should be from Saudi Arabia.

"Frankly, Saudi Arabia has been aiding and abetting this by really for decades funding radical Islam and many say that many of the arms that Saudi Arabia has been funneling into Syria have gone into supporting ISIS. ... There's nobody in the surrounding region that says they're in favor of ISIS now. They need to step up and put their soldiers and their money where their mouth is," said Paul.

He said he has always agreed that ISIS is a threat, but never agreed with sending arms to rebels in Syria, arguing many of those ended up in the hands of ISIS.

Paul said he would vote "yes" on authorizing military action against ISIS, but believes the resolution should have a "sunset provision" that would require another debate in Congress after a year.

"I don't like the idea that one generation can vote to bind another generation to war forever," said Paul, noting that he's "upset" that a vote from 15 years ago is being used by some as a justification for military force today.

Watch the full interview above.