US President Donald Trump temporarily lifted restrictions on foreign shipping from the US mainland to Puerto Rico on Thursday to help get supplies quickly to the US territory as it reels from the devastation of Hurricane Maria.

But even so, the island still faces huge logistical hurdles to distribute badly needed food, fuel and drinking water. Most of the Caribbean island's 3.4 million people also are without electricity.

Brock Long, the administrator of the Federal Emergency Management Agency (FEMA), said he was dissatisfied with the federal response but that relief operations had been hampered by damage to the air traffic control system, airports and ports.

Shipping containers have been piling up at Puerto Rico's ports in the aftermath of Maria, which struck on Sept. 20, causing widespread flooding and major damage to homes, roads and other infrastructure.

Puerto Rico's governor, Ricardo Rossello, had sought a waiver of the Jones Act, which limits shipping between US ports to US owned-and-operated vessels, to ensure there was no impediment to bringing in supplies.

The waiver, which will be in force for 10 days and will cover all products shipped to Puerto Rico, was signed on Thursday morning by acting Department of Homeland Security Secretary Elaine Duke, the DHS said in a statement.

Unlike Brock, Duke told reporters on Thursday she was ‘very satisfied’ with the federal response to Maria. ‘The relief effort is under control. It is proceeding very well,’ she said.

The US government has periodically lifted the Jones Act for a temporary period following violent storms, including after hurricanes Harvey and Irma, which hit Texas and Florida in late August and earlier this month.

Critics had charged the government was slow to issue such a waiver for Puerto Rico after Maria, which was the most powerful hurricane to hit the island in nearly 90 years.

Trump had issued a temporary waiver for the shipping of petroleum on Sept. 8, soon after the departments of Defense and Energy made recommendations to do so in response to Harvey, which hit Texas on Aug. 25 damaging refineries and pipelines. No federal departments recommended a waiver for Puerto Rico, however, leaving the requests to lawmakers and Puerto Rico’s governor.

Even as FEMA and the US military have stepped up relief efforts, many residents have been exasperated at the prolonged lack of electricity, reliable supplies of drinking water and other essentials.

In the old town in the capital, San Juan, a smattering of shops were beginning to open but there was still a lack of basic services.

Radamez Montañez, a building administrator from the municipality of Carolina, east of San Juan, said he had been without water and electricity at home since Hurricane Irma grazed past the island earlier this month. ‘It's chaos, total chaos,’ he said. ‘Everybody is in total chaos.’

Critics of the Trump administration have said the island is not getting the same response from Washington as it would if it were a US state, even though its residents are US citizens.

'THANK YOU' TO TRUMP

White House spokeswoman Sarah Sanders announced on Twitter that Trump had authorized the Jones Act waiver at Rossello's request. The governor, who has staunchly defended Trump's response to the hurricane, retweeted her post with a ‘Thank you @POTUS’ - referring to the Republican president's official Twitter handle.

In Washington, some politicians said the Jones Act waiver should last longer or that the law should be completely repealed.

Even if the waiver helps speed cargo to the island, Puerto Rico is still struggling to move supplies around.

‘Really our biggest challenge has been the logistical assets to try to get some of the food and some of the water to different areas of Puerto Rico,’ Rossello said interview with MSNBC on Thursday.

‘We need truck drivers,’ he said, adding he had asked the Department of Defense to send troops to help with transportation.

‘The food is here, the water is here. We welcome more help. But critically, what we need is equipment,’ and people, either national or state troops, Rossello said.

FEMA's Long told CNN that relief operations had been hindered by damage to the transport infrastructure, adding, ‘The situation is not allowing things to move as quickly as we would all like.

‘No, I'm not satisfied because the fact is, is that we will not be satisfied until we stabilize the situation, which is why we work day in and day out, hour after hour, to try to alleviate the situation,’ he said.

Military personnel are playing a sizeable role. The military had delivered fuel to nine hospitals and helped establish more than 100 distribution centers for food and water on the island, the Pentagon said on Thursday.

It also was shipping a large generator to power a radar center to help air traffic control in San Juan and other airports. Five of six priority sea ports were open, although some had restrictions on the size of the vessel or were for daylight use only, the Pentagon said.

A barge with 100 defense trucks carrying diesel and gasoline was expected to arrive in San Juan by Monday.

In Washington, the Transportation Department on Thursday made $40 million in ‘quick release’ Emergency Relief funds to help restore essential service on roads and bridges damaged by Maria throughout Puerto Rico. The money was in addition to $2.5 million in emergency funds awarded to Puerto Rico after Irma, according to the department’s Federal Highway Administration.