Final answer:
When countries make agreements to defend and support one another, it's called a security pact, like NATO. These pacts involve military protection and can extend to economic and environmental issues, being fundamental to international security and law.
Step-by-step explanation:
When countries agree or promise to defend and help another country, this is typically referred to as a security pact. A security pact is a formal agreement among multiple states to provide mutual support in case of a military threat or attack. For example, the North Atlantic Treaty Organization (NATO) is one such security pact, which was formed to safeguard US allies in Europe from a Soviet attack. Countries such as the United States, Canada, and various European nations agreed that an attack on one member would be considered an attack on all, enabling a collective defense under Article 5 of the NATO Treaty.
Another aspect of international alliances may involve economic assistance or sanctions to signal displeasure with a country's behavior or to support a threatened nation in accordance with treaty commitments. Treaties can extend to various domains, including military, economic, and even environmental concerns as seen with the Paris Climate Accord, or human rights with the Universal Declaration of Human Rights. The dynamic between military protection, alliance commitments, and international law plays a critical role in global politics and the preservation of national and international security.