In a long-awaited report on FEMA's response to 2017's hurricanes, the agency said it had underestimated how devastating a hurricane could be to Puerto Rico. FEMA said it failed to grasp the "insufficiently maintained infrastructure," especially the power grid, of the island.

FEMA said its plans "did not anticipate the massive requirements to deliver electricity, telecommunications, and fuel sector utilities with air and sea movement" on Puerto Rico. Additionally, FEMA did not anticipate the "need to move critical pharmaceutical supplies off Puerto Rico to meet national demands."

FEMA noted that 2017's three major hurricanes -- Harvey, Irma and Maria -- were three of the costliest on record. The report also said the agency was not prepared to deal with such massive storms in quick succession and at the same time as destructive wildfires in California. In response to Hurricane Irma at the end of August, FEMA said it gave out more than 80 percent of its supplies from the Caribbean Distribution Center warehouse, and there was no time to replenish before Maria hit on Sept. 19.

Overall, the 2017 hurricane season was the costliest on record, with the storms causing $265 billion in damage. Nearly five million people registered for FEMA assistance from the storms and the California wildfires, more than in the last 10 years combined.

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FEMA said it had made adaptations to their policies and programs after the storms. Department of Homeland Security Secretary Kristjen Nielson, who oversees FEMA, said in a statement after the report was released that "2017 taught us that we need to further strengthen the nation's ability to rapidly stabilize critical lifelines."

President Trump said in October he felt "we have done a great job with the almost impossible situation in Puerto Rico." His response to the storm has been criticized, especially after San Juan Mayor Carmen Yulín Cruz, accused the Trump administration of "killing us with the inefficiency."

Although the U.S. government claimed the death toll from Maria was 64 people, researchers at Harvard concluded in May the storm led to the deaths of 4,600 people. Earlier independent investigations had put the death toll closer to 1,000.