The so-called backstop clause is the only way London and the European Union have identified a way to prevent the reestablishment of a physical border between the Republic of Ireland and the British province of Northern Ireland after Brexit, reports Tuesday, August 20, the European Commission, reacting to the alternative proposed by Boris Johnson.

The British Prime Minister has written to Donald Tusk, President of the European Council, to propose replacing this safeguard clause with alternative provisions before the end of the transition period.

>> What to see: What is the "backstop"?

"The letter does not provide a legal operational solution to prevent the return of a physical border on the island of Ireland," said Natasha Bertaud, spokeswoman for the European Commission, during a press briefing. "Our position on the backstop is well known (...) This is the only way identified by both parties so far to honor this commitment."

"Avoid a physical border on the island of Ireland"

Donald Tusk, meanwhile, judged that Boris Johnson had not proposed any "realistic alternative". "The backstop is insurance to avoid a physical border on the island of Ireland until an alternative is found," he wrote on Twitter.

The backstop is an insurance to avoid a hard border on the island of Ireland unless and until an alternative is found. Those against the backstop and not proposing realistic alternatives in fact support reestablishing a border. Even if they do not admit it.

Donald Tusk (@eucopresident) August 20, 2019

"Those who are against the backstop and do not offer realistic alternatives are actually in favor of restoring a border, even if they do not admit it."

The backstop is a clause of last resort which provides that, for lack of a better solution after a transitional period, and to avoid the return of a border between the British province of Northern Ireland and the Republic of Ireland. Ireland, the entire UK remains in a "single customs territory" with the EU.

Boris Johnson believes that this clause, which crystallizes the opposition of the "brexiters" to the agreement negotiated by Theresa May, undermines British sovereignty.

With Reuters