August 26, 1990

LEAD: In the last week the United States crossed a threshold in confronting Iraq over its Aug. 2 invasion of Kuwait. It became more than a nation responding firmly to an international crisis; in its collective consciousness and in cold fact, it began preparing for war.

LEAD: A decade ago, Arleen Uerling was working in a restaurant in Yakima, Wash., when Mohammed Tayeh walked in, ''and it was love at first sight,'' her mother said. Two years later they were married and headed for Kuwait, where, until the Iraqi invasion Aug. 2, Mr. Tayeh had a catering service and Arleen

LEAD: Allyn Sielaff had a progressive reputation when he took over New York City's jails. Now critics are asking whether isolation made him blind to tension at Rikers Island. Page 40.

LEAD: THE threat of tactical warfare in the Middle East, coupled with Department of Defense delays in proposals for a new generation of military aircraft, are fueling predictions that the department may alter plans to end production of the Grumman F-14 fighter jet.

LEAD: OUT in the midday sun on one recent 90-degree afternoon, Juliana Barrett and Margaret Ardwin were paddling their canoe upstream through Pratt Cove, a freshwater tidal marsh near the mouth of the Connecticut River. Oblivious to the heat, skidding into islands of wild rice, they were searching for a rare species of bidens, a member of the daisy family.