Law enforcement officials are quoted in media reports saying the timing of the letters may just be a coincidence.
The mailings were sent from Los Angeles to several members of Congress and contained a photo with a man standing in front of the recruiting center.
The small recruiting station was damaged Thursday in a pre-dawn bombing that shattered glass and buckled the front door. The center was empty at the time and no one was injured.
New York City Police Commissioner Ray Kelly said a witness reported seeing an individual who was acting suspiciously near the center just before the explosion.
Kelly said the witness said the person was riding a bicycle, wearing a hood and dark clothing, and carrying a backpack. He said Thursday's blast is similar to attacks on the British consulate in 2005, and the Mexican consulate last year.
The recruiting station is on a small traffic island in the center of Times Square, surrounded by theaters, restaurants and retail stores, in an area known as the "crossroads of the world."
Source: By VOA News