An attack outside the Louvre and fallout from the newly imposed U.S. travel ban have complicated bids by Paris and Los Angeles to host the 2024 Olympics.

On Friday, officials from both cities presented their Bid Books — the last major filing with the International Olympic Committee before it awards the games in September.

But both presentations were overshadowed by problems: In Paris, a knife attack on a soldier outside the Louvre raised more questions about the city's ability to host a secure Olympics. And the Los Angeles bid is dealing with the U.S. government's recently imposed international travel ban that led to Iran's decision not to allow U.S. wrestlers into the country for a meet this month.

Budapest, Hungary, is the other candidate.