When hitler sent troops into the rhineland in 1936 and austria in 1938, other european nations

The answer is that the other European nations offered no resistance and did not try to stop Hitler either politically or militarily.

Explanation:

This inactivity of Other European nations, specially Britain and France, gave Hitler both the confidence and the opportunity to attack Poland and the rest of the Europe!

When Hitler sent troops into the Rhineland in 1936 and Austria in 1938, other European nations  offered no resistance, as they were carrying a policy of appeasement on Germany.

Explanation:

Appeasement was the policy adopted by the United Kingdom and its allies in the 1930s with the aim of stopping Hitler's expansionist aims and consequently avoiding military intervention against Germany.

It was evident to European governments how the policies of the German government, aimed at achieving Germany's economic and military supremacy in Europe, as well as the spread of nationalistic culture aimed at affirming the supremacy of the German race, would quickly lead to the outbreak of a conflict. Despite this tense political picture, the British and French governments believed that a war conflict should be avoided.

In 1938, after the annexation of Austria, Hitler agreed to meet in Munich the French Prime Minister and the British Prime Minister and together they signed an agreement that basically accepted almost literally the German requests for occupation of the Czechoslovakian territory of the Sudetenland. The Munich Pact temporarily offered an alternative way out of the war and represented the pinnacle of appeasement policy, but also represented the inability of the United Kingdom and France to react to German expansionism.

United States would be neutral.