Excursion in history
First, you need to recall the history of domestic launchers for weapons of strategic missile forces. The first rockets, which appeared at the end of the forties, were proposed to be used with open installations located at a suitable position without the construction of large special objects. However, this installation did not provide any protection for the rocket, and therefore in the early fifties the development of more advanced systems with better protection was launched.

Protective device of the launch shaft for the P-36M rocket. Photo of the Strategic Missile Forces / pressa-rvsn.livejournal.com
By the mid-fifties, some new missiles "went underground" with the help of mine launchers. The reinforced concrete structure was not exposed to external influences, and moreover, it provided protection of the missile from missile and bomb strikes, including with the use of certain types of nuclear weapons. However, the mines did not prove to be the ideal solution to the problem, and therefore the designers started to create mobile ground-based missile systems.
The idea of the PGRK was first implemented in the field of operational tactical missiles, but later found application in other classes. In the eighties, the first ICBMs appeared on such launchers. To date, mobile complexes have become the most important and integral element of the rocket forces, successfully complementing the stationary silos.
The current position
According to open sources, now the Russian Strategic Missile Forces are on duty on the order of 300 intercontinental missiles of various types, both in launch mines and on mobile complexes. In this case, we are talking about five types of missiles, two of which are not rigidly tied to the launcher class. Three other models can be used only with PGRK or only with silos.
The oldest and smallest in the missile forces are ICBMs of the type UR-100НТТХ. Under such products, all 30 starting mines of one of the Strategic Missile Forces connections are now given. Slightly newer P-36М / М2 missiles are available in 46 units, and all of them are located only in the mine launchers. Duty is about 35 missiles RT-2PM "Topol", which are used with mobile launchers. In recent decades, almost 80 of the RT-2PM2 Topol-M missiles and about 110 PC-24 Yars products have been put on duty. It is the Topol-M and Yars missiles that can work with both mines and self-propelled machines.
Available data allow us to determine how many missiles are in the mines, and how many are transported by special vehicles. 30 UR-100N UTTH missiles, 46 Р-36М, 60 РТ-2ПМ2 and 20 РС-24 - total 156 units are on duty at silos. On mobile performance complexes, 35 of the RT-2PM, 18 Topol-M and 90 Yarsov missiles are a total of 143 products. Thus, the missiles are distributed between the silo and the PGRK almost equally, with a slight margin in favor of the former. The planned replacement of old missiles with new ones may lead to some changes in this ratio, but without any particular advantage for one or another class of installations.
Mines: Pros and Cons
The most widespread type of launchers in the Russian Strategic Missile Forces - both active and unused on duty - are mine. With them, first of all, old types of rockets are used, which cannot be exploited on the PGRK. However, new models are created taking into account the available material part and can also be applied to silos.

Internal equipment of silo for Р-36М. Photo Rbase.new-factoria.ru
The advantages of the silo launcher are obvious. An underground structure made of reinforced concrete of high strength provides a high level of missile protection and related equipment. For the guaranteed destruction of the rocket and the calculation of such an installation - depending on the design and characteristics of the latter - a high-power nuclear charge and a direct hit in the mine area are necessary. In other situations, the missile system can remain operational and take part in a retaliatory strike.
An indirect advantage of silos is less severe restrictions on the size and mass of the rocket. This allows the rocket to be equipped with larger and heavier as well as more powerful military equipment. It is well known that domestic missiles UR-100N UTTH and P-36М are equipped with a split head with several warheads, while Topol and Topol-M each carry one warhead. It is also possible to give the rocket a larger fuel supply and thereby improve its flight data.
It should be noted that the main advantage of the launch shaft is associated with its main drawback. The launch complex is in one place, and the probable enemy knows his coordinates in advance. As a result, it can deliver the first blow against the silo with more powerful and long-range missiles. To solve this problem, it is necessary to strengthen the protection of the mine in one way or another.
The simplest option to improve protection is to use more powerful building structures, which, incidentally, has a negative impact on the complexity and cost of construction. An alternative solution - active protection complexes. As early as the eighties, the development of special anti-missile systems for the timely interception of the enemy’s military units began in our country. KAZ had to shoot down threatening objects and thereby ensure a safe launch from the silo. In the late nineties, the domestic project of the Mozyr complex was stopped, but several years ago new research in this area started.
Pros and cons of mobility
Almost half of the Russian ICBMs are currently operated on mobile ground-based missile systems. Obviously, such a technique, like stationary mines, has both advantages and disadvantages. At the same time, the combination of positive and negative features is such that the command of the Strategic Missile Forces considered it necessary to operate two types of equipment simultaneously.

Mine head and missile UR-100H UTTH. Photo Rbase.new-factoria.ru
The main advantage of the PGRK is its mobility. Self-propelled launcher, command and control vehicles during combat duty do not remain in place. They constantly move between the base, equipped positions and defenses. This, at a minimum, makes it difficult to determine the current location of the complex and, therefore, prevents the enemy from organizing the first disarming strike. Naturally, the prepared positions may be known to the enemy in advance, but before the attack he will have to figure out which of them have real targets.
However, mobility leads to certain problems, for getting rid of which certain measures are necessary. PGRK on duty may be ambushed by saboteurs. When attacking a complex, the enemy uses small arms or explosive devices. However, in this case, the maintenance of the complex on duty includes several different machines for different purposes. First of all, launchers are accompanied by armored personnel carriers and escort soldiers. If necessary, they must take the fight and repel the attack.
Especially for the Strategic Missile Forces were created so-called. remote clearance machine and anti-sabotage combat vehicle. This technique is capable of reconnaissance, timely find the enemy or explosive devices, as well as destroy detected threats. In addition, adopted so-called. engineering and disguise machine. This sample is capable of leaving false traces of the PGRK column, misleading the enemy’s reconnaissance.

Download rocket RT-2PM2 Topol-M in silo. Photo of the Ministry of Defense of the Russian Federation
A significant drawback of the PGRK is the restrictions on the carrying capacity, leading to a reduction in combat performance. Modern Topol and Topol-M missiles have a starting weight of less than 50 t due to the characteristics of the chassis. It is for this reason that they could not get a split head and carry one charge each. However, in the new project “Yars” this problem is solved, and the rocket is equipped with several warheads.
Development prospects
Currently, the Russian defense industry is launching new PC-24 missiles and transferring them to the Strategic Missile Forces to be put on duty or sent to arsenals. Depending on the current needs of the troops, the Yars rocket may be loaded into the silo or installed on the PGRK. Like the older Topol-M missile, the new PC-24 is made universal in basing. This fact may hint at the further development of the Strategic Missile Forces and their weapons.
Apparently, the relatively lightweight ICBMs of existing and prospective types will be used in the foreseeable future together with the PGRK and the silo silo. Due to this, it will be possible to realize all the main advantages of the launchers of two types while reducing the negative impact of existing disadvantages. In other words, some missiles will be able to be protected by reinforced concrete structures, but they will be at risk of a first strike, while others will escape observation, although they will require the assistance of a number of special machines.
The situation is different in the field of heavy ICBMs. In the foreseeable future, the Strategic Missile Forces plans to complete the operation of the old UR-100N UTTH and P-36M rockets, which, for obvious reasons, can only work with launch shafts. The outdated missiles will be replaced by a new PC-28 “Sarmat” product, which also belongs to the heavy class. Before its adoption, a certain number of available silos will have to be repaired and upgraded. Thus, the rocket troops will receive new weapons, but they will not have to spend time and money on building the required facilities from scratch.
In all likelihood, in the medium term, the RS-24 "Yars" and RS-28 "Sarmat" missile systems will form the basis of the armaments of the Strategic Missile Forces of Russia. Products of the Topol family will have the same position as Р-36М or УР-100НТТТХ currently. They will still remain in service, but their number and role should be gradually reduced.
It is not known how modern and prospective rockets will be distributed between the PGRK and the silo silo in the future. Obvious is the fact that the heavy "Sarmatians" can be on duty only in the mines. Part of the lighter Yarsov will remain in the silo, while the others will continue to be used together with self-propelled launchers. It is possible that the ratio of the number of mines and mobile complexes will remain at the current level, although changes are possible.
Which is better?
Comparing the different ways of basing and operating intercontinental ballistic missiles, it is difficult not to ask the expected question: which one is better? But in this formulation, this question is not entirely correct. As in the case of other weapons and military equipment, the correct question is different: which way is better for the tasks assigned? The answer is obvious. Both the silo launcher and the mobile soil complex, at least at the concept level, meet the requirements set for them and correspond to the tasks performed.

Start "Topol" with a mobile launcher. Photo of the Ministry of Defense of the Russian Federation
Moreover, the joint operation of the launchers of the two classes provides certain advantages. Due to it, in practice it is possible to realize the advantages of both systems, as well as partially get rid of their characteristic minuses. Also, we should not forget about the ongoing updating of the material part of the rocket forces. It is planned to modernize part of the existing silos, and new PGRK variants are being developed. It is to be expected that new and improved complexes will compare favorably with their predecessors.
In the context of different ways of basing an ICBM, the question “what is better?” Does not make much sense, but you can also find an acceptable answer for it. Most likely, it is worth answering "both that, and another". Mine launchers and mobile ground systems for many years of operation have had time to demonstrate their capabilities and have proven themselves. In addition, a successful structure of rocket forces, based on both types of launchers, has now been formed. Probably, such a structure will be able to change significantly only in the event of the appearance of fundamentally new ground launchers.
On the materials of the sites:
http://mil.ru/
http://tass.ru/
http://ria.ru/
http://rbase.new-factoria.ru/
http://russianforces.org/
http://russianarms.ru/