Norfolk Southern Corp.’s top executive defended the railroad’s stock buybacks in a tense exchange with US lawmakers, saying the financial strategy doesn’t sacrifice rail safety.

In a hearing Wednesday over the recent derailment of a Norfolk Southern train in Ohio, Democratic Senator Peter Welch of Vermont grilled Chief Executive Officer Alan Shaw on his company’s repurchases, which totaled $3.1 billion last year. Welch asked whether Norfolk Southern would pause the activity until it had fulfilled the commitments made to residents at the crash site.

“Senator, stock buybacks never come at the expense of safety,” Shaw said.

Welch shot back: “I take that as that you will continue with your plan on the buyback.”

Shaw was appearing for the second time before the Senate in the past two weeks as lawmakers consider legislation to tighten freight rail safety. The Norfolk Southern train derailed Feb. 3, spilling chemicals in the small Ohio town of East Palestine and generating political outrage.