U.S. Treasury yields declined Monday as fresh military escalation between the U.S. and Iran pushed oil prices higher, while eurozone government bond yields moved up. The 10-year Bund yield reached a new 15-year high. The retreat in Treasury yields offset a sharp rise in short-dated yields on Friday, which followed Federal Reserve Chairman Kevin Warsh’s emphasis on returning inflation to the 2% target. His remarks suggested that interest rates might need to rise, making shorter-maturity government debt more sensitive to the prospect of tighter monetary policy.