European Council President Donald Tusk confirmed on Twitter that he had received Britain's Brexit notification letter on Wednesday, saying, "after nine months the UK has delivered Brexit."
He tweeted a photograph of himself receiving the small, business-style white document from the British ambassador to the EU, Tim Barrow. It contains a signed letter from British Prime Minister Theresa May. Its delivery starts a two-year countdown to withdrawal.
"Now is the time for us to come together and be united across this house (of Parliament) and across this country to ensure that we work for the best possible deal for the United Kingdom, and the best possible future for us all," May told the Parliament.
The two-year period for Britain and the European Union to settle the terms of their split is very tight, a spokesman for the German Foreign Ministry said.
"The time-frame is damn narrow," Martin Schaefer said at a regular government news conference.