The U.S. services sector contracted in March, snapping 13 months of growth, as the war took its toll on the economy.

The Institute for Supply Management reported Thursday that its index of non-manufacturing activity deteriorated to 47.9 in March from 53.9 in the previous month. The reading was well below economists forecast of 52.5.

The index is comprised mostly of services, which make up two-thirds of U.S. economic output. Index readings under 50 indicate a contraction.

ISM said that war worries were key in pushing the overall index lower. The non-manufacturing index’s components were broadly weak. The new orders index slipped to 47.7 from 53 in February.. Pricing pressures also continued, with that index up to 62 from 60.9.