Definition: In this task, you need to generate an appropriate title for the given summary of some paragraph. The generated title must be short and should include the main topic of the given text. Your summary should be less than 20 words long.
Input: The former Irish prime minister Bertie Ahern has warned dissident Republicans could use a re-introduction of border posts in Northern Ireland to justify their campaign of violence.

Bertie Ahern warns of danger of 'hard' NI border