BRUSSELS (Reuters) - The European Union warned Britain on Wednesday that it would react swiftly if Britain acted alone to change post-Brexit trading arrangements for Northern Ireland, but did not spell out what its steps might be.
"Trust, which should be at the heart of every partnership, needs to be restored," Maros Sefcovic, the vice president of the European Commission overseeing EU-UK relations, told a news conference after a meeting with British counterpart David Frost.
"If the UK were to take further unilateral action in the coming weeks, the EU will not be shy in reacting swiftly, firmly and resolutely to ensure that the UK abides by its international law obligations.
"Pacta sunt servanda," he added, using the Latin for 'agreements must be kept'.