A mountain of food, water and other vital supplies has arrived in Puerto Rico's main Port of San Juan.

But a shortage of truckers and the island's devastated infrastructure are making it tough to move aid to where it's needed most, officials say.

At least 10,000 containers of supplies -- including food, water and medicine -- were sitting Thursday at the San Juan port, said Jose Ayala, the Crowley shipping company's vice president in Puerto Rico.

Part of the reason for the distribution backlog is that only 20% of truck drivers have reported back to work since Hurricane Maria swept through, according to a representative for Puerto Rican Gov. Ricardo Rosselló.

On top of that, a diesel fuel shortage and a tangle of blocked roads mean the distribution of supplies is extremely challenging. Even contacting drivers is a problem because cell towers are still down.

"When we say we that we don't have truck drivers, we mean that we have not been able to contact them," Rosselló said.

On Thursday the White House authorized a 10-day waiver of the Jones Act, a federal law that limits shipping to US ports by foreign vessels. Puerto Rico's governor and other US officials had argued that a waiver would expedite supplies to the island.

But as Ayala has indicated, shipping companies already have aid and supplies either waiting at the port to be delivered -- or held up at ports on the US mainland.

Of the 3,000 containers that Crowley alone had sent to San Juan's port as of Wednesday, only 4% had been dispatched from there, Ayala said.

Ayala said the company can't get enough truck drivers or trucks filled up with diesel to pick up supplies for distribution across the island.

"The problem has been with the logistics, the parts of the supply chain that move the cargo from our terminal to the shelves or to the tables of the people in Puerto Rico," Ayala said Wednesday. "This hurricane was catastrophic."

Meanwhile, Puerto Ricans are waiting hours in line to get gas, food and cash. Gas stations and supermarkets are rationing supplies, while banks are running low on cash.

It should be noted - and never is - that the road network in Puerto Rico is similar to that of a third world country. Transportation infrastructure was horrible before the hurricane and has only gotten worse in the aftermath. Paved roads are blocked with trees, debris from the storm, and downed power lines. Dirt roads, of which there are many, have been washed away or are a sea of mud.

Who is responsible for all those containers still sitting on the docks? Obviously, local governments should have been better prepared to receive the aid and distribute it. Why didn't the loud mouth mayor of San Juan have truck drivers waiting in the wings to distribute the food? She couldn't foresee the cell towers being blown over? She couldn't imagine blocked roads? 

I suppose FEMA could have hired 20,000 truck drivers and sent them to Puerto Rico, but with the roads impassable, how would the aid have reached those in need? 

The exact same situation was present in the aftermath of hurricane Katrina. Convoys of thousands of trucks containing relief supplies were backed up to Fort Worth, TX, according to a statement by FEMA at the time that appeared in the New Orleans Times-Picayune  (link broken.). It's not that the response by the feds was totally inadequate. It's that the devastation was so severe and so widespread, that many of the roads and bridges leading into New Orleans were blocked or washed out.

We didn't use to politicize hurricane relief efforts. It was assumed that everthing that could be done was being done. At least, we assumed that when Bill Clinton was president.

Now, of course, the goal is to get Trump any way possible. The president is making it ridiculously easy for the media to pile on, as he has turned his statements and tweets - delivered from a golf course - into boosting his administration's image.

As much as the media has politicized the response to the disaster, Trump has gone them one better.