Israel’s security service, Shin Bet, has arrested about 30 Palestinians in the West Bank over the past few months on suspicion of working to rebuild the local infrastructure of Hamas, the Islamic militant group, according to a statement issued Monday. Hamas won legislative elections in the West Bank and Gaza in 2006 and took full control of Gaza a year later. Its rival, the Fatah-dominated Palestinian Authority, has limited control in the Israeli-occupied West Bank and has also worked to suppress Hamas there. Israeli security officials said those arrested were members of a “field command” responsible for strengthening Hamas’s presence in some West Bank universities.