A day after President Donald Trump finally broke his silence on North Korea after the isolated nation twice provoked its geopolitical adversaries in the span of just four days, Yonhap is reporting that the US  sent four F-35B stealth jets and two nuclear-capable B-1B strategic bombers to train with South Korea's F-15K fighter jets over the Korean Peninsula on Thursday in what it described as an "unprecedented" escalation of the allies' military response to N.Korea's provocations.