"We cannot allow this to happen", Trump said. The visiting ministers' itinerary will continue until Friday, when they are expected to meet with the South Korean foreign and defense ministers to further discuss a range of issues concerning bilateral cooperation and regional security.
The four aircraft then flew across the peninsula and staged another round of a firing exercise over the Yellow Sea before the two B-IBs returned home, the South Korean Joint Chiefs of Staff (JCS) said.
"This drill was part of a routine deployment training aimed at enhancing deterrence" against the North's nuclear threats, the JCS said in a statement.
The B-1Bs also conducted exercises with Japan's Air Force in what the United States statement called a "sequenced bilateral mission".
Responding to a question, the United States president said it is a problem that has to be solved.
It did not say when the Hawaii-based submarine with a crew of around 150 would depart the peninsula.
"The U.S. has made clear military options remain on the table in the event of the worst outcome and Australia made it clear we are working closely with the U.S. and South Korea without having to engage in hypotheticals".
Julie Bishop insists US President Donald Trump and his Secretary of State Rex Tillerson's wildly different attitudes towards diplomacy and North Korea are both right.
He added that North Korea would not rule out "the use of the most extreme measures in response".
"You see that in the actions of [North Korean leader] Kim Jong Un, reaching out to Republicans to say 'what's this guy about?' said Kinzinger".
And the hermit kingdom responded by stressing their right to nuclear weapons, labelling Trump "deranged" in the process.