This was the Millenium Challenge in 2002. Another interesting war simulation that seems the U.S. did not learn their lesson.

https://warontherocks.com/2015/11/millennium-challenge-the-r...

I guess the simplest answer is they didn't launch an attack because they couldn't. Specialized torpedo boats cannot generally penetrate a destroyer or cruiser screen without assistance. There is no viable way to even get into position to threaten a carrier as such a movement will be detected on radar long before a threat materializes. Even when American ships engaged in offensive operations close to the north Vietnamese coast they came out on top in clashes involving patrol boats making a large offensive operation unappealing.

The red force in the millenium challenge had access to significant capabilities that Iraq and Vietnam did not have access to such as incredibly accurate anti-ship cruise missiles.