Meaning that an attack is "highly likely" from 'international' terrorists.
Theresa May was careful to stress the 'international' aspect, and went on to say that there is no intelligence of such a threat.
What game is being played here? Has the level been raised because of someone's gut instinct? Is it really a hidden warning to home-grown jihadis not to try anything? Is it a 'gee-up' to the public for us to keep on being alert because there is a feeling that we have been slacking?