NEW YORK - Peacekeepers across the world are having to cope with increasingly dangerous environments and need help to do their work, according to the head of the United Nations.

In an opinion piece in The Boston Globe, Secretary-General Antonio Guterres on Monday wrote that "too often, United Nations peace operations face a gap between our goals and the means we have to achieve them."

He said peacekeepers, known as the "blue helmets" for their iconic headgear, are being increasingly targeted by extremists and groups fighting in conflict zones.