There has been some criticism of the response, particularly in British overseas territories.
Here's a snapshot of international assistance so far:
Britain
Britain has pledged £32 million (35 million euros, $42 million) in assistance and sent 10 flights of aid since Friday to its affected Caribbean territories, the British Virgin Islands and the Anguilla archipelago, with six people killed in the storm.
The flights have carried medical supplies, emergency shelter kits, rations and clean water to affected islands, as well as engineers and military personnel.
Almost 700 British troops have been deployed and 17 officers from London's Metropolitan Police have also been sent following reports of looting.
The RFA Mounts Bay, a Royal Navy ship which was in the region when the mega-storm hit, has been deployed.
A second warship, HMS Ocean, is being loaded with disaster relief supplies in Gibraltar before it sets off for the region as expected on Tuesday.
But Britain's response to Irma has been criticised by some local inhabitants as too slow and some Britons have voiced frustration over Britain's failure to evacuate their loved ones from the area.
Foreign Minister Boris Johnson has rejected the criticism, calling it "completely unjustified".
"I am confident we are doing everything we possibly can to help British nationals," Johnson told the BBC.
France
France said 10 people died on St Barts and on its side of St Martin, a joint French-Dutch territory where Irma left most of the 80,000 inhabitants homeless.
French aid includes helicopters, engineering equipment, medical supplies and a million litres of water, as the three water-treatment plants on the island will be knocked out for months.
The French defence ministry also announced that a military ship, set to leave France on Tuesday, would carry an additional four helicopters and 1,000 tonnes of supplies, and be used as a "floating hospital".
About 1,500 people have been deployed so far including emergency personnel, troops and police officers.
Evacuations started in earnest again on Sunday after the Grand-Case airport on St Martin was reopened.
The French energy group EDF said it would send 140 tonnes of electrical equipment including generators and pumps from nearby Guadeloupe as soon as conditions permit.
French President Emmanuel Macron is due to travel to St Martin later on Monday.
Opposition figures have accused Macron's fledgling government of bungling the response to the disaster, with the radical leftist leader Jean-Luc Melenchon calling for a parliamentary inquiry.
The Netherlands
The Dutch defence ministry had stationed two naval vessels in the area before the storm, carrying a helicopter and supplies.
Four people have lost their lives on the Dutch side of St Martin, known as Sint Maarten.
So far four military flights loaded with troops and aid - including food, water, medicines and medical equipment - have been sent.
The Red Cross has also sent a plane with 60 tonnes of aid on board in collaboration with French-Dutch carrier Air France-KLM.
The first group of wounded and sick survivors were evacuated by helicopter off the island late Friday.
Tourists have also begun to be evacuated by both the travel company TUI, which operates its own planes, and the Dutch military.
Mass distribution of food and water was due to start Monday on St Martin, and desalination equipment and purification tablets were also on their way.
A 59-member search-and-rescue team composed of doctors, rescue personnel and emergency workers was also dispatched Monday to the island.
Dutch King Willem-Alexander arrived on Sunday in Curacao, another Dutch Caribbean island, to view the aid operation and was to travel to St Martin on Monday, Dutch media reported.
There has been some criticism that the government has not moved fast enough.
"They reacted far too late. The French were much quicker on St Martin to evacuate people," Kitty Algra, a tourist, told the Dutch newspaper AD.
United States
The US military has evacuated US citizens from St Martin to Puerto Rico. The US estimates that 2,000 to 3,000 US citizens still need to leave the affected areas.
US amphibious assault ships have also been assisting residents of the US Virgin Islands, where four people were killed by the storm.
The USS Abraham Lincoln, with 24 helicopters aboard, arrived off Florida on Sunday to conduct relief operations in southern Florida and along the Florida Keys.
Additionally, the Pentagon said about 4,600 troops were helping in the Virgin Islands-Puerto Rico region, and the US Marines were helping transfer UK counterparts in St Croix on to the British Virgin Islands.
The US military's Southern Command has coordinated the evacuation of 1,904 US- and non-US people from St Martin over the past three days, the Pentagon said.
