Cuba poses a "national security threat" to the US and the likelihood of a peaceful agreement is "not high", US Secretary of State Marco Rubio has said, BBC reported. 

His comments come just a day after the US charged Cuba's former president Raul Castro with murder over the 1996 downing of two planes resulting in the killing of US nationals.

Rubio said Washington's preference was "a diplomatic solution" but warned that President Donald Trump had the right and obligation to protect his country against any threat.