Who or what was the "new scare" or menace in america during the early cold war era?

The "New Scare" represented the communist threat to destroy the capitilist countries and bring them under their control.

Explanation:

Anticommunism is a historical phenomenon dating back to the nineteenth century, found in both Europe and America. It is present not only in speeches that preach the persecution of communists, but also in a set of ideals in defense of private property that pose communism as a threat to democracy.

Based on this context, the "New Scare" was proposed as a way of placing communism as a real and frightening threat. The New Scare preached that the communist countries, led by the USSR, could dominate and destroy the capitalist countries, setting up chaos and terror in those countries.

The image below is the cover of a 1947 comic book in the United States that uses the concept of "New Scare" to show a future where the country is dominated by communists.

the American people tame  their country's frontiers in order to make safe and expand the boundaries of their country.

Explanation:

The people of American tame  their country's frontiers for making the in order to make safe and expand the boundaries of their country on the barren vast land that were present beyond the frontier line. According to Frederick Jackson Turner, the environment on the frontier is hard and the advancement of the frontier occurs in order to include the frontier areas in the country and proper government should be made in these areas. These areas were also captured due to increase in population.