Complex sentence: Higgins defends the oil fields plan, claiming that there will be a day in which oil shortages will cause a major economic crisis for the country, and that Americans will want the government to use any means necessary to obtain the oil.
Split into simpler sentences: Higgins defends the oil fields plan, claiming that there will be a day in which oil shortages will cause a major economic crisis for the country. And when that day comes, Americans will want the government to use any means necessary to obtain the oil.