1.   In the early months, secrecy shrouded their activities.

2.   The company is one of the largest arms traders in the United States but its activities are shrouded in secrecy.

3.   As a precaution against terrorists, NASA shrouded their activities until they arrived at the shuttle.

4.   In addition, NASA shrouded the activities of the U.S., Russian and French astronauts and cosmonauts until they were climbing aboard their spaceship.