It is immoral for a government to enter a war unless

The answer is D.

A. Governments increase casualties by joining wars in other countries
This option discusses the increase in casualties due to governments joining wars in other countries. While it may imply negative consequences, it doesn't directly address the argument's premise of the necessity for international approval before entering a war without citizens being attacked. It lacks a direct correlation to the argument's context.

B. Some governments have caused international turmoil by entering wars without international approval
This option indicates that some governments have led to international turmoil by engaging in wars without obtaining international approval. While this supports the notion that entering wars without approval can result in negative consequences, it doesn't directly address the argument's central premise—specifically emphasizing the necessity for international approval before entering a war when citizens have not been attacked.

C. There is usually international approval for a government that goes to war after its citizens are attacked
This option hints at international approval more likely being granted when a government responds to an attack on its citizens. However, it does not directly address the argument's main point of requiring international approval before entering a war without citizens being attacked.

D. A government will not receive international approval to join a war when its citizens have not been attacked
This statement directly supports the argument by asserting that a government is less likely to obtain international approval for a war when its citizens have not been attacked. It strongly aligns with the argument's premise, emphasizing the necessity for international approval before engaging in such wars.

E. Governments often save lives by entering wars in other countries
This option presents a potential positive outcome of governments entering wars in foreign territories. However, it doesn't specifically support the argument's assertion that international approval should be sought before entering a war without citizens being attacked.