Puerto Rico, the US Virgin Islands and other Caribbean islands were devastated by the storm. Relief agencies are seeking donations, as well as food, water, and medical supplies.
After Boris Johnson said the response was "piecemeal", Brigadier John Ridge told BuzzFeed News: "I wouldn't say it was hand-to-mouth from my perspective."
The storm, which rapidly strengthened on Monday, is expected to charge through the Caribbean this week, pummeling islands already devastated by Hurricane Irma.
"It's worse than Afghanistan," said one military officer struggling to deal with a humanitarian crisis on the British territory as another hurricane approaches.
Look at Obama riding that wave.
The prime minister launched a defence of Britain's overseas territories – and said the US, China, and India should follow the UK's lead on financial transparency.
Over 120,000 offshore companies and trusts brought into public view.