Now you know what a nuclear physics package is and how it is designed. But it is not enough to develop and produce nuclear physics package to acquire nuclear weapon. There is another key component of nuclear weapon. A nuclear weapon have to produce certain effect in a certain time and place. So, the country need to develop and produce also delivery vehicles to deliver the weapons to the target. They are called launchers or delivery vehicles. As you remember, the first nuclear weapon ever used was a bomb. The delivery vehicle for a bomb is an airplane. A specific airplane called heavy bomber. Since that time, many other means to deliver nuclear weapons were developed. From artillery shells to long-range intercontinental ballistic missiles. There are several types of delivery vehicles which have strategic significance. What launching systems could be used to deliver a nuclear weapon to a target? Supposed we have two opposing countries, country A and B, divided by notion. The first way to deliver a nuclear weapon is to use long-range heavy strategic bomber. These bomber will fly all the way to the target, and then will drop the bomb to the target. The other way is to use a ballistic missile. The ballistic missile can be launched directly from the territory of the state A. The ballistic missile will fly outside of the atmosphere, and then launch one or several nuclear warheads to the target. Or, a ballistic missile can be launched from a submarine. In this case, the ballistic missile will fly the same way and launch one or several warheads to the target. The first type of ballistic missile is called intercontinental ballistic missile or ICBM. The second type launched from submarine is called submarine-launched ballistic missile. We can divide all the launchers into categories, mobile and stationary. In these pictures, you can see the only stationary launching system, a silo-based ballistic missile. The combination of various launching systems create a nuclear forces. For the United States and Russia, this is so-called nuclear triad. The nuclear triad is a complex in which all elements complement each other. I should highlight here that's not all the states which possess nuclear weapons have nuclear triads. The architecture of nuclear forces of each state is an excessive question and we will not spend our time on this now. In a nuclear triad, all of the elements complement each other. Any type of delivery vehicles has its strong and weak features. In a nuclear triad, weakness of one element is compensated by the merits of another. This is precisely why the United States and Russia were committed to developing the triad. From the early years of national nuclear weapons programs, the Soviets and Americans were working to develop nuclear triads. In future presentations this week, we will explore features of each component of the triad and talk about air, land, and sea components. Now, let's have a look at the nuclear triad as a complex. The nuclear triad is a system of interconnected elements. An important thing to note, is that the proportion are unique for each national nuclear force. Let's have a look at the map. Russia has a huge territory, but fairly limited access to oceans. Russia covers more than 17 billion square kilometers. Although the coastline is very low, Russian Navy has only two points of access to the world ocean. You can see two red arrows on the map that shows these points of access. The United States have smaller territory but very long coastal lines with comfortable access to oceans. So, this is why Russia always had more land-based systems while the United States relied more on the naval component.