The fortification of Busan as a temporary capital of the government of South Korea was tremendous. Dubbed as the "Second Battle of the Busan Perimeter", a name taken from a battle during the Korean War in where U.S. and ROK soldiers valiantly defended the port city against the North Koreans, it was where the joint-ROK and USFK forces managed to hold the infection back. Bridges, roads, and railroads were destroyed with airstrikes, blocked with vehicles, or purposely set on fire. Additional refugees came in from sea, aided by ROKN naval vessels and civilian merchant ships. Others were resettled in the resort island of Jeju, acting as the last resort fallback should the fortifications fall. The Korean Coast Guard, disbanded by President Park in 2014 after the
M/V Sewol sinking, was unofficially pressed into service, using whatever police or civilian volunteers they could muster, since all reserves in the ROK Army and Marines have been mobilized. Those that could have made it Busan were ordered into the city's defense, but there were still isolated military units up north towards the 38th Parallel, either isolated by the infected or holding out in hastily fortified garrisons awaiting for resupply or extraction.
A single KTX trained approached the tunnel fortification leading into Busan. It was unresponsive and upon closer inspection by ROK Army scouts perched atop containers using high-powered binoculars, the train was overrun with the infected. Immediately, it was fired upon by ROK AH-1 Cobra gunships. The infected then spilled out of the train and ran towards the fortifications, where they were fired upon by snipers and machine gunners. Those that managed to reach the fortifications were electrocuted in the hastily-erected electrical fences.
By 5:00 PM, July 21, 2016, there were roughly 1,300,000 refugees that made it to the Busan perimeter, the Jeju Island safe-zone, and various islands in the southern area of the peninsula. One of them was what seemed to be a mother and a child. Almost mistaken to be one of the infected and fired upon, they were immediately rescued by the defenders of the Busan fortifications. They were then taken to a refugee camp, where they were interviewed on what happened where they revealed their name, Seong-kyeong, and the child, Su-an. Seong-kyeong admitted to the military officials and the authorities that they were the only survivors of the last KTX train that left Seoul earlier that morning, that Su-an's father was killed because of the infected, that her husband was killed as well and that she is not the mother of the child. Because of times of an emergency, the authorities allowed Seong-kyeong to accompany Su-an in the Busan Safe-Zone. Su-an would later be given stress de-briefing sessions before meeting her mother, who divorced with her late-father some time ago. Su-an's mother would then thank Seong-kyeong for protecting her child as they were transferred to Jeju Island for the sake of the child and Seong-kyeong's unborn child.
Westward towards the Pacific, the RIMPAC exercises commence in Hawaii. However, due to the events in South Korea, the ROK-N contingent is ordered back home to partake in the retaking of the peninsula. Because of the timely event of the naval exercises, Admiral Scott H. Swift has requested most ships coming from different nations participating in the Hawaii exercises to stem towards of the Korean peninsula in support for the humanitarian crisis. The Hawaii exercises ultimately came to an end as participating ships from Australia, Brunei, Canada, Chile, China, France, India, Indonesia, Japan, New Zealand, and the United States plotted a course towards South Korea. The ships came in formation around the USS
John C. Stennis aircraft carrier, in what is known as the largest naval cooperation in human history.
RIMPAC 2016 participants lead by the USS
John C. Stennis en route to the Korean Peninsula.
The USS
Ronald Reagan, currently deployed to the South China Sea with the Carrier Strike Group 5 in response to the UN Arbitration of China vs. the Philippines, was ordered to support to head to Korea by the U.S. Pacific Command.
For the first time since the conclusion of the Third Taiwan Strait crisis in 1996, the largest show of force of American military might was coming to East Asia.
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Author's Notes:
EDIT (September 29, 2019): I just found out the Reagan was in the South China Sea area at that time in July 2016 so it would make sense the U.S. would redeploy it to support their South Korean allies as the Stennis was still in the Pacific.