British Prime Minister David Cameron announced to members of parliament the current Iraq crisis may have inevitable consequences for the U.K., including a direct terrorist attack in the country.

In addition to announcing an increase of humanitarian aid for displaced Iraqis, Cameron warned the members of parliament (MPs) that any illusions that instability in Iraq from Islamist extremism is unrelated to the U.K. will come back to haunt them, according to the BBC.

The Prime Minister will be discussing the U.K.’s role in Iraq with the National Security Council, reported the Independent, and beforehand he warned MPs against thinking that “the deteriorating Middle East security situation ‘won't affect us’.”

Up to 400 British nationals are participating in the attacks alongside terror forces in Syria, the BBC reported, but it was not specified if this number included British citizens as well. Cameron warned the MPs about British citizens traveling to Iraq and Syria, joining the militants, then going back to the U.K., as well as ISIS plans “to attack us here at home in the U.K.,” reports the Independent.

Cameron said the U.K. has “considerably less information” about what is happening in Iraq, according to the Telegraph.

“The estimates are now this is a greater threat to the U.K. than the return of foreign jihadist or fighters from Afghanistan or Pakistan region.”