By june of 1940, hitler had already done which of the following? check all that apply.

he had invaded russia.
he had conquered norway.
he had conquered great britain.
he had invaded the netherlands
he had pushed allied forces out of france.
he had forced the united states to join the war.

The quote below is an excerpt from the charter of the united nations: "the purposes of the united nations are: to maintain international peace and security, and to that end: to take effective collective measures for the prevention and removal of threats to the peace, and for the suppression of acts of aggression or other breaches of the peace, and to bring about by peaceful means, and in conformity with the principles of justice and international law, adjustment or settlement of international disputes or situations which might lead to a breach of the peace . " source:this section implies that the united nations is prepared to do what to keep world peace?