Here is the full list of all 37 Third Front achievements.
Found 500 diversionists
Complete the USSR campaign
500 units of equipment were purchased
Complete the Alliance campaign
Captured all the cities
Complete Germany campaign
250 cities are captured
Found 125 diversionists
Earned 10,000,000
200 cities are captured
125 units of equipment were purchased
The main building is improved to level 40
150 cities are captured
The main building is improved to level 30
100 cities are captured
The main building is improved to level 20
Earned 2,500,000
25 diversions prevented
25 units of equipment were purchased
50 cities are captured
Found 25 diversionists
The main building is improved to level 10
The population reached a mark of 100,000,000
The population reached a mark of 50,000,000
20 cities are captured
The main building is improved to level 5
10 diversions prevented
The population reached a mark of 20,000,000
10 cities are captured
5 diversions prevented
Found 5 diversionists
The population reached a mark of 5,000,000
Earned 500,000
5 units of equipment were purchased
Diversion prevented
3 cities are captured
Earned 50,000