European central bankers left the Jackson Hole symposium concerned that recent US Treasury interventions could strain long-standing norms of global financial cooperation. Unannounced yen intervention, Treasury bond buybacks and uncertainty over Fed dollar swap lines have raised concerns about Washingtons growing role in global financial markets.

Recent US Treasury interventions to prop up the Japanese yen and to lower longer-term US borrowing costs were particularly concerning

Europe's central bankers are leaving an annual getaway with their United States counterparts far from reassured that long-standing norms in global cooperation remain intact and…