The main reason why this was the case is because Industrialization was an incredibly new phenomenon, and very few people could have predicted just how bad it was for the environment and for people's health.
United States involvement in the Boxer Rebellion would have contradicted the ideals George Washington laid out in his farewell address. It also would have violated the Monroe Doctrine by becoming involved in Europe's subject matters.
True.
This was evidenced by the Neutrality Acts of 1930s.
The 1st Neutrality Act was the prohibition of export of "arms, ammunition, and implements of war" from the U.S. to foreign nations at war. The act requires arms manufacturer in the United States to apply for export license before they can exports arms to foreign nations.
The Neutrality Act of 1937 forbids U.S. Citizens from boarding belligerent ships. American ships were also prevented by this Act to transport arms to belligerents even if the arms were made outside the U.S. The Act also gave the President the right to bar belligerent ships from all U.S. waters.
However, there was an exception to this Act. Belligerent nations were allowed, at the discretion of the president, to acquire any items except arms from the United States, as long as they immediately pay for these items and carry them on non-American ships. This provision is called the "cash-and-carry".
The final Neutrality Act was passed on November 1939. This act lifted the arms embargo and put all trade with belligerent nations under the terms of "cash-and-carry". The ban on loans and barring of American ships transporting goods to belligerent nations still remain in effect.
