WASHINGTON—A measure of U.S. business activity increased to an eight-month high in March, fueled by strong demand for both goods and services, but Russia’s war against Ukraine hurt sentiment. S&P Global said on Thursday its flash U.S. Composite PMI Output Index, which tracks the manufacturing and services sectors, rose to a reading of 58.5 this month. That was the highest reading since July 2021 and followed 55.9 in February. A reading above 50 indicates growth in the private sector. The continued rebound from a slump in January mostly reflected pent-up demand and the easing of COVID-19 restrictions across the country, as well as less severe supply chain disruptions. The flash composite orders index rose to a nine-month high, with businesses reporting that “a greater availability of inputs allowed them to be more competitive and win new customers.” With new orders and unfinished work piling up, companies hired workers at the …