Please answer a question about the following article about 51st state:

During World War II, when Denmark was occupied by Nazi Germany, the United States briefly controlled Greenland for battlefields and protection. In 1946, the United States offered to buy Greenland from Denmark for $100 million ($1.2 billion today) but Denmark refused to sell it. Several politicians and others have in recent years argued that Greenland could hypothetically be in a better financial situation as a part of the United States; for instance mentioned by professor Gudmundur Alfredsson at University of Akureyri in 2014. One of the actual reasons behind US interest in Greenland could be the vast natural resources of the island. According to Wikileaks, the U.S. appears to be highly interested in investing in the resource base of the island and in tapping the vast expected hydrocarbons off the Greenlandic coast.

What is one reason the US would be interested in Greenland?
the vast expected hydrocarbons off the Greenlandic coast.