What happens after Train to Busan?

Going to watch it, but would like it more if they focus on the South Korean Army moving in to retake the country, something like 28 Weeks later type of thing.

Here is another graphic I could use for reference:


Source: US-S.Korea Talks Abruptly Halted Over Trump’s $4.7BN Price Tag For Basing Troops

I'm still researching what U.S. Army units are deployed near the DMZ-JSA. 

United States
(~19,060 personnel, not counting DOD civilian employees and civilian dependents)
United States Army
- Eighth United States Army (Yongsan Garrison - safe)
- 2nd Infantry Division (Camp Humphreys - safe)
- 604th Air Support Operations Squadron (Camp Humphreys - safe)
- United States Army Medical Department Activities Korea
- 65th Medical Brigade
US Army Medical Materiel Center-Korea
25th Transportation Battalion
- Far East District of the United States Army Corps of Engineers
- 94th Army Air and Missile Defense Command (Kunsan AB)

35th Air Defense Artillery Brigade
2nd Battalion, 1st Air Defense Artillery Regiment – MIM-104 Patriot missile batteries
Light-armored vehicles: Humvees
Tanks and Armored Fighting Vehicles: M1A1 Abrams, M2 Bradley, Stryker IFV
Aviation: UH-60 Blackhawks, AH-64 Apaches

United States Air Force
--Pacific Air Forces
---Seventh Air Force
----8th Fighter Wing (Kunsan Air Base)
8th Operations Group
35th Fighter Squadron - F-16C/D Fighting Falcon
80th Fighter Squadron - F-16C/D Fighting Falcon
-----51st Fighter Wing (Osan Air Base)
51st Operations Group
25th Fighter Squadron - A-10C Thunderbolt II
36th Fighter Squadron - F-16C/D Fighting Falcom
---Fifth Air Force
----18th Wing
18th Operations Group
33rd Rescue Squadron - Detachment 1 (GSU) - HH-60G Pave Hawk
---Air Mobility Command
----USAF Expeditionary Center
515th Air Mobility Operations Wing
515th Air Mobility Operations Group
731st Air Mobility Squadron (GSU) - C-130 Hercules, C-17 Globemaster, C-5 Galaxy

United States Navy
Seventh Fleet
- USS Ashland (LPD-20)
2 x LCACs
1 x LCU
3 x CH-46 Sea Knight helictopers
2 x MV-22 Osprey
- USS Bonhomme Richard (LHD-6)
20 x AV-8B Harrier
4 x AH-1W/Z Super Cobra/Viper attack helicopter
20 x MV-22B Osprey
4 x CH-53E Super Stallion
6 x SH-60F Seahawk ASW helicopter
- P-8A Poseidon maritime patrol aircraft from USFJ bases.
- P-3C Orion maritime patrol aircraft from USFJ bases

United States Marine Corps
- III Marine Expeditionary Force
- ~2,000 Marines aboard the USS Green Bay and the USS Bonhomme Richard along numerous LAV-25s, M1A2 Abrams, AAV7s, Humvees, etc.

Japan
Japan Maritime Self-Defense Force
- JS Hyūga (DDH-181)
3 x SH-60K Seahawk​
1 x AW101​
Other aircraft​
JS Kirishima (DDG-174)
1 x SH-60K Seahawk
- P-3C Orion maritime patrol craft

Japan Air Self-Defense Force
- 4 x Mitsubishi F-2 fighter jets

China
People's Liberation Army
PLA Ground Force (deployed at the Sino-Korean Border)
- 20,000 troops
- 80 armored vehicles: Type 11 assault vehicle, Type 90 (WZ-551), PGZ-95, various SPGs, and AA-vehicles
- 50 x Type 99 MBT
- 30 x Helicopters: Z-10, Z-8, Z-11, Gazelle

PLA Navy (deployed at the Yellow Sea)
North Sea Fleet (Qingdao Naval Base)
- 1 x Type 052D Destroyer (NATO/OSD: Luyang III-class destroyer)

• Xining (117)​

- 2 x Type 051C Destroyer (NATO/OSD: Luzhou-class destroyer)

• Shenyang (115)​

• Shijiazhuang (116)

- Harbin SH-5 and KJ-2000 maritime patrol planes

PLA Air Force
- Fighter jets: Su-30 (Flanker-C), Su-35 (Flanker-E), J-10 (Firebird), J-11 (Flanker-L).
- Cargo: Il-28
- AWACS: KJ-2000

Russia
Russian Ground Forces (at the Russo-Korean border near Vladivostok)
- 1,500 personnel from the Far Eastern Military District
- 63 APCs/IFVs: BTR-80, BMP-7, ZSU-23-4 (Shilka), 2K22 Tunguska (Grison)
- 75 tanks: T-90 MBT, T-72
- 23 helicopters: Mi-8 (Hip), Mi-24 (Hind), Mi-28 (Havoc)

Russian Air Force
- Fighter jets: MiG-29 (Fulcrum), MiG-35 (Fulcrum-F), Su-27 (Flanker), Su-30 (Flanker-C), Su-35 (Flanker-E) etc.
- AWACS: Beriev A-50 (Mainstay)

Russian Navy
Russian Pacific Fleet
- 1 x Slava-class destroyer

• Varyag​
  

- 1 x Udaloy I-class destroyer

• Marshal Shaposhnikov​
  

- 6 x Il-38 (Dolphin) maritime patrol plane
Note: Among the 20,000 ground troops deployed by the Russian Ground Forces, an estimate 500-1,000 are believed to be Russian Naval Infantry
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On DeviantArt: www.deviantart.com/godemperorgillan/art/Initial-international-resoponse-to-KPV-843460455

Well I actually had a difficult time researching what Chinese and Russian forces are at their respective borders. It's virtually unknown to the West as of OTL. Even Global Security has no such database.

What I found however was this:
PLA Northern Theater Command - The Northern Theater Command's Area of Responsibility (AOR) consists of the northeastern region of China, within the provinces of Heilongjiang, Jilin, Liaoning, Shandong, and Inner Mongolia. The AOR also includes areas around the border of Mongolia, Russian Siberia, and North Korea, as well as the shoreline around the Bohai Bay and Yellow Sea. e Northern Theater Command shares borders with North Korea, Russia and Mongolia.

Eastern Military District - It is one of the five military districts of the Russian Armed Forces, with its jurisdiction within the Far Eastern Federal District of the country. The Eastern Military District was created as part of the 2008 military reforms, and founded by Presidential Decree №1144 signed on September 20, 2010, to replace the Far East Military District with the addition of the Transbaikal section of the Siberian Military District. The district began operation on October 21, 2010, under the command of Admiral Konstantin Sidenko. The Eastern Military District is the second largest military district in Russia by geographic size at 7,000,000 square kilometers (2,700,000 sq mi). The district contains 12 federal subjects of Russia: Amur Oblast, Buryatia, Chukotka Autonomous Okrug, Jewish Autonomous Oblast, Kamchatka Krai, Khabarovsk Krai, Magadan Oblast, Primorsky Krai, Sakha Republic, Sakhalin Oblast, Zabaykalsky Krai.

I wonder how Japan is handling this crisis ?