The U.S. will send the hospital ship USNS Comfort to Puerto Rico in a ramped up military response, hampered by poor communications, to the devastation caused by Hurricane Maria, the Pentagon said Wednesday.

"We need to understand what [they] need in order to get the right stuff there to the right place," Air Force Gen. Lori Robinson, commander of U.S. Northern Command, said in an acknowledgement that initial assessments failed to gauge the scope of the disaster.

To speed the flow of aid, the military response was being shifted from a sea-based relief effort from the Amphibious Ready Group led by the amphibious assault ship Kearsarge to an Army-led forward headquarters on the ground in Puerto Rico, the Defense Department said in a statement.

Army Brig. Gen. Rick Kim, deputy commander of U.S. Army North, was deploying Wednesday to Puerto Rico to set up a Joint Force Land Component Commander-Forward (JFLCC) base on the island to manage the relief and recovery effort on the ground, DoD said.

Following pleas by island officials for medical aid, the Comfort was preparing to leave port in Norfolk, Virginia but will probably take several days to deploy as it takes on crew and supplies, according to Federal Emergency Management Agency Director Brock Long and the Navy.

At least 10 persons have died in the aftermath of Hurricane Maria and San Juan Mayor Carmen Yulin Cruz warned that many more were at grave risk while waiting for help.

In an emotional plea, Yulin Cruz said Puerto Ricans were in a "life and death" struggle without power, food or water.

"I know that leaders aren't supposed to cry and especially not on TV, but we are having a humanitarian crisis," Yulín Cruz told WUSA-TV. "It's life or death, every moment we spend planning in a meeting or every moment we spend just not getting the help we're supposed to get, people are starting to die."

At a Women In Defense summit in Washington, Robinson, who is overseeing the military response in Puerto Rico, said that it has been difficult thus far to direct the relief.

The problem was in getting a grip on what was needed -- and where -- "on the ground so we don't add to the burden to make sure you put the right capability and capacity in -- whether it's power generators, whether it's water, food," she said.

Robinson said she was in constant contact with the other services to ask "Do you have the things that you need in order to sustain until we figure out more [of] what's happening in Puerto Rico?"

At the direction of the FEMA and local governors, NorthCom has overall responsibility for military relief and recovery efforts in Puerto Rico and the U.S. Virgin Islands, while U.S. Southern Command, through the State Department, was overseeing operations in the Caribbean's Leeward Islands.

The military initially moved quickly to put in place water, food and medical aid for the 3.4 million U.S. citizens on the island who have mostly been without power and communications since Maria hit last week.

On Tuesday, President Donald Trump said that the relief effort was "going well," but Joint Chiefs Chairman Gen. Joseph Dunford told a Senate Armed Services hearing that recovery operations have been limited by damage caused to ports and airfields.

"Roughly 44 percent of the population remains without drinking water," DoD said in a statement. Of the 69 hospitals on the island, about 59 were believed to be operational but their status and whether they have power was unknown, DoD said.

The deployment of more ships, aircraft and troops to Puerto Rico followed criticism of the adequacy of the U.S. response thus far and DoD's acknowledgment that poor communications may have affected initial assessments of the disaster.

Earlier this week, former Secretary of State Hillary Clinton sent out a Tweet urging the deployment of the Comfort and House Minority Leader Nancy Pelosi, D-California, called on Congress to pass an emergency aid bill.

The DoD statement said that improving communications were now "providing a clearer picture of the extent of the storm damage and the magnitude of the response challenge."

"Given the changing scope and conditions, DoD will adjust its concept of operations in Puerto Rico and transition from a short term, sea-based response to a predominantly land-based effort designed to provide robust, longer term support to FEMA and the Territory," the DoD statement said.

In a separate statement, the Army said that more than 3,800 soldiers and U.S. Army Corps of Engineers civilians were now in Puerto Rico and the U.S. Virgin Islands.

The Army has 16 aircraft and 520 trucked committed to the relief effort, and an additional eight HH-60 helicopters were expected to arrive in the next 24 hours, the statement said.

The Puerto Rico Army National Guard was primarily focused on route clearance and re-establishing communications on the island, the statement said.

With the electrical grid down, the Department of Defense said that one of the urgent priorities was getting fuel to Puerto Rico to power generators.

The fuel crisis has led members of Congress to urge Trump to suspend shipping restrictions under the Jones Act that bars foreign-flagged vessels from picking up and delivering fuel between U.S. ports.

The Jones Act was suspended from Sept. 8 through Sept. 22 to allow shipments to Texas and Florida after Hurricanes Harvey and Irma. Puerto Rico was also included under that suspension, but the suspension ended on Sept. 22 and has not been renewed for Puerto Rico.

Sen. John McCain, R-Ariz., chairman of the Senate Armed Services Committee, called on the Trump administration to issue another suspension of the Jones Act for Puerto Rico and ultimately "a full repeal of this archaic and burdensome act."

"These emergency waivers have been valuable in speeding up recovery efforts in the impacted regions," McCain said.

When asked Wednesday about another Jones Act suspension, Trump said "Well, we're thinking about that, but we have a lot of shippers and a lot of people and a lot of people who work in the shipping industry that don't want the Jones Act lifted. And we have a lot of ships out there right now."

"And Puerto Rico is a very difficult situation," Trump said at the White House before leaving for Indiana to discuss tax reform. "I mean, that place was just destroyed. I mean, that place was flattened. That is a really tough situation. I feel so bad for those people.

--Richard Sisk can be reached at Richard.Sisk@Military.com

-- Oriana Pawlyk can be reached at oriana.pawlyk@military.com. Follow her on Twitter at @Oriana0214.