Different enemy factions will launch raids on Liberal strongholds. During a raid, enemy forces surround the target hideout. The following factions can raid your hideouts, and the criteria for their raids are also posted:
Police will raid your hideouts if you have a sufficient amount of heat. They bring SWAT officers and normal police officers.
The National Guard will raid you if you have previously fought off police raids. They bring soldiers and, in worst case scenarios, bombers and tanks.
The Conservative Crime Squad may raid any hideout that has heat, regardless of how low it is. They often bring mercenaries, rednecks, and Elite Security guards.
The Corporations will hire mercenaries to raid you if you have provoked them either by attacking the Corporate HQ or the CEO Residence, as well as for publishing articles about the Corporations in the Liberal Guardian.
The CIA act similar to the corporations, and will raid you if provoked.
From there, they will decide to either starve out your Liberals or, if they are feeling confident, assault your base.
It may wise to wait out a siege for as long as possible, as this will provoke an assault, in which your traps and cameras, if you have any installed, will come into effect. Do note that the enemy may try to weaken your hideout before an assault, by doing various things such as bombarding positions with aircraft or cutting the power.