Retiring Republican Rep. John Shimkus is ending his support for President Donald Trump after this week‘s withdrawal of U.S. troops from the Syria-Turkey border, calling the move “despicable.”

The Illinois Republican told St. Louis radio station KMOX on Thursday that after he learned about the withdrawal, he told his own chief of staff to “pull my name off the ‘I support Donald Trump’ list.”

Shimkus expanded his comments later Thursday, saying in a statement: “While my votes will continue to support the president’s domestic policy agenda, because of this terrible foreign policy decision I asked that my name be removed from his campaign’s official list of supporters.”

Shimkus joins a wave of Republicans who have denounced Trump for essentially leaving Syrian Kurds to fend for themselves against the Turkish military. Even close allies of the president, like Sen. Lindsey Graham (R-S.C.) and Rep. Liz Cheney (R-Wy.), the third-ranking Republican in the House, criticized the president’s move, especially after Turkish forces began an incursion into northern Syria on Wednesday.