The 24-foot boat involved in a deadly clash with Cuba's coast guard was stolen in the Florida Keys and had American citizens aboard, U.S. officials tell Axios.Why it matters: Four people were killed and six injured in the incident Wednesday, the latest source of tension between the U.S. and Cuba as the Trump administration increases pressure on Cuba's communist regime.Secretary of State Marco Rubio said the U.S. is investigating the incident and has officially asked Cuba for access to the six in...