“It’s not a private matter on property issues,” he argued. “It has to do with security; it has to do with human rights.”

Mr. Moskowitz is among the most prominent of a group of wealthy, ardently pro-Israel Americans, including Jews and evangelical Christians, who have financed development in West Bank settlements that are widely seen around the world as violating international law. From 2000 to 2010, at least 40 American groups collected more than $200 million in tax-deductible gifts to build schools, synagogues, apartments and community centers in such settlements.

Last year, the American casino tycoon Sheldon Adelson made what he said was his first investment in the region that is not inside Israel’s 1948 borders, pledging $25 million to build a medical school at Ariel University, part of a large settlement city that is among the most vexing for two-state mapmakers.

“My many years in business have taught me that when a crack opens up in a certain spot, it must not just be filled in, but rather the whole wall has to be strengthened, and sometimes the entire building,” Mr. Adelson said in a statement at the time. “The donation to Ariel University is about building a Zionist wall in place of the crack.”

Mr. Moskowitz, a retired physician who built his wealth through hospitals and bingo halls, has been involved in some of the most provocative settlement projects, buying property in Arab neighborhoods just outside Jerusalem’s Old City and turning them into apartments or yeshivas, leading to intense clashes. He owns the Shepherd Hotel, an East Jerusalem landmark that Israel began demolishing in 2011, exacerbating tensions with Washington.

In Bruchin, a settlement deep in the West Bank, the Moskowitz name adorns a day care center that was built while the community was considered forbidden even by Israel (a court in 2012 retroactively legalized it).