Because it could. These countries (Baltic States) have strategic value because of their location (ports, places for airports). Also the governing ideology in the SU that time was a communism which supported a global revolution, uniting the whole world under in a communist utopia.
It varied on what the political situation was. In Asia, more precisely in India, colonization came as a result of trading with western companies which eventually made the whole place dependent on trading with the west and made the companies rich enough so that they could subjugate the locals.
In Africa, colonization mostly occurred due to the need of resources. In some places like the continental parts of Africa it was about physical resources that required mining and similar things. In coastal Africa, it was about the workforce with the slave trade running rampant and a lot of money being involved.
South-East Asian countries that were colonized were often colonized as a response to enemy occupation or freeing them from other colonizers. For example, places like Vietnam and Philippines were occupied during wars and colonization came by providing help to the local population in fighting those wars after which they remained colonies of those who helped them.<span />
The Roosevelt Corollary (1904) to the Monroe Doctrine proclaimed the right o the United States to 1. intervene in the internal affairs of Latin American nations. The Corollary was to the earlier Monroe Doctrine, which told European powers to stay our of Western Hemispheric affairs. Roosevelt's reasoning was that the United States would have to intervene were Latin American countries to weak to provide funds or infrastructure necessary for the support of trade. If those countries could not support trade, the US would have to intervene because a failure of trade would, purportedly, negatively affect the US's ability to manage the affairs of the region.
The right answer for the question that is being asked and shown above is that: "the necessity of developing a system for military transport." Legislation passed in the 1950s to fund an interstate highway system was primarily in response to <span>the necessity of developing a system for military transport</span>