A deranged man was busted when he smashed a window to enter a United Nations building early Saturday, police said.

The suspect, identified as a 44-year-old Connecticut resident, tried to enter the highly secure building by climbing a fence near the FDR Drive and 42nd Street, cops said.

He then used a brick to smash a first-floor window.

United Nations security officers quickly apprehended the suspect and held him for police.

The man was being evaluated at Bellevue Hospital, and was expected to be charged with criminal trespass.