A growing row over Theresa May's apparent threat to pull security co-operation unless Brussels agrees a trade deal is a "misunderstanding", a Cabinet minister has insisted.
In her letter to European Council president Donald Tusk triggering Article 50, the Prime Minister warned that failure to reach a comprehensive settlement would lead to a weakening of co-operation in the fight against crime and terrorism.
Critics accused the Prime Minister of trying to make a trade-off between security and commerce.
Work and Pensions Secretary Damian Green said the two issues had been mentioned side by side because they were "all bound up in our membership of the European Union".
"It's not a threat, I think that's the misunderstanding," he told BBC Two's Newsnight. "It's absolutely not a threat."
In a "historic moment from which there can be no turning back", Mrs May set the country on the path to life outside the European Union when she triggered Article 50 on Wednesday.
The Prime Minister immediately ran into resistance from German Chancellor Angela Merkel and the European Parliament over her goal of conducting negotiations on Britain's trade relations with Europe at the same time as talks on arrangements for Brexit.
Foreign Secretary Boris Johnson, w riting in the Daily Telegraph, said: "It is our clear desire and intention that we should continue to play a role as one of the indispensable guarantors of peace and stability in our continent.
"We want to continue to work with our counterparts on defence co-operation, intelligence sharing, counter-terrorism, foreign policy co-ordination - and much else besides - on an intergovernmental level.
"At the same time, the PM is right to spell out her vision of a Britain outside the single market - and outside the EU legal order - but able none the less to continue the trading relationship that is so important for businesses and consumers both sides of the Channel."
The Prime Minister's letter formally beginning the UK's departure from the European Union has recognised the unique relationship between the UK and the Republic of Ireland and the importance of maintaining peace in Northern Ireland.
A Northern Ireland businessman has said he is weighing up relocating south of the border as Theresa May prepares to trigger Article 50 today. The move marks the beginning of the formal exit process and starts the clock on negotiations over leaving.
Article 50 of the Lisbon Treaty sets out a two-year deadline for completion of the withdrawal negotiations. But what happens within that period is less clear. Here are some of the milestones expected along the way to Britain’s final withdrawal.