Sen. Lindsey Graham (R-S.C.) toured tunnels on Sunday in southern Israel dug by the terrorist group Hamas, which controls Gaza, to infiltrate and attack Israel—part of seeing sites and meeting leaders on a trip to the Jewish state.

“The tunnels have been used by groups like Hamas to smuggle weapons and terrorize Israeli citizens,” tweeted Graham.

“Cost of tunnel = cost of 2 new schools = cost of 30 new homes. #Hamas consistently makes the wrong choices for the people of #Gaza. Heartbreaking,” tweeted Friedman.

On Monday, Graham had breakfast with U.S. Ambassador to Israel David Friedman and Israeli Prime Minister Benjamin Netanyahu, according to the prime minister’s office.