"why should any "rules of engagement" have been in force?" - Steve Shaw

In 1988? In the Persian Gulf? Are you kidding?

Look up The Tanker War - 1984 to 1988 in which 546 commercial vessels were damaged and 430 civilian merchant sailors were killed.

The "Tanker War" began in the spring of 1984, started by the Iraqis in an attempt at provoking the Iranians into closing the Straits of Hormuz, which would have brought the USA directly into the conflict. The Iranians responded as follows:

"The Iranian Navy imposed a naval blockade of Iraq, using its British-built frigates to stop and inspect any ships thought to be trading with Iraq. They operated with virtual impunity, as Iraqi pilots had little training in hitting naval targets. Some Iranian warships attacked tankers with ship-to-ship missiles, while others used their radars to guide land-based anti-ship missiles to their targets. Iran began to rely on its new Revolutionary Guard's navy, which used Boghammar speedboats: fitted with rocket launchers, RPGs, and heavy machine guns, these speedboats would launch surprise attacks against tankers and cause substantial damage. Iran also used aircraft and helicopters to launch Maverick missiles and unguided rockets at tankers."

This ultimately resulted in the following:

"Iranian speedboat attacks on Kuwaiti shipping led Kuwait to formally petition foreign powers on 1 November 1986 to protect its shipping. The Soviet Union agreed to charter tankers starting in 1987, and the United States Navy offered to provide protection for foreign tankers reflagged and flying the U.S. flag starting 7 March 1987 in Operation Earnest Will."

In a live shooting environment where there are innocent third parties present "Rules of Engagement" are always required.