United States Ambassador to Israel Dan Shapiro voiced nearly unprecedented criticism against Israel's settlements in the West Bank on Monday. Shapiro praised progress made in the investigation into the arson-murder in the Palestinian village of Duma, but emphasized the inadequate response by Israeli authorities to settler violence against Palestinians.

Speaking at the Institute for National Security Studies (INSS) conference in Tel Aviv, Shapiro said "Too much Israeli vigilantism in the West Bank goes on unchecked," adding that "there is a lack of thorough investigations at times it seems Israel has two standards of adherence to rule of law in the West Bank - one for Israelis and one for Palestinians."

Shapiro added that the two-state solution is the only way to prevent Israel from turning into a bi-national state, and said a way must be found to preserve its viability. He noted that the American administration is "concerned and perplexed" in wake of the Israeli government's policy on the settlements, "which raise questions about Israeli intentions."

The Prime Minister's Office rejected allegations of double standards shortly after Shapiro's speech and issued a response saying "the ambassador's statements, on the day when a mother of six who was murdered is buried, and on a day when a pregnant woman is stabbed – are unacceptable and wrong.

"Israel enforces the law on Israelis and Palestinians. The onus for the stalemate in the diplomatic process is the Palestinian Authority, which continues to incite and refuses negotiations," it said.

Shapiro's comments are the latest in a string of critical remarks voiced by the U.S at the Israeli government. Two weeks ago, the U.S. said it was "deeply concerned" after Defense Minister Moshe Ya'alon approved the establishment of a new settlement inside a church compound in the West Bank, State Department Spokesman John Kirby said during a press briefing.

Ya'alon's decision, Kirby said, shows a lack of commitment to the two-state solution on Israel's part.The State department spokesman offered an unusually detailed account of the American concerns, and said that the decision joins the fact that 70 percent of Area C in the West Bank, where Israel has full security and civilian control, have already been designated as state lands and a part of the municipal area of local and regional councils. Ya'alon's decision "only expands this significant majority of the West Bank that has already been claimed for exclusive Israeli use," he stressed.

Last week, Shapiro met with Justice Minister Ayelet Shaked, with the U.S. embassy issuing a highly irregular statement regarding her so-called "NGO Transparency Bill."

“Ambassador Shapiro sought more information about the draft legislation from the Minister, and noted the U.S. government’s concerns on the matter,” stated the announcement.

The bill would require Israeli NGOs that receive a majority of their funding from foreign governments to be labeled as such when in the Knesset. A senior American official remarked that Shapiro made it clear to Shaked that in contrast to her assertions, the bill has no similarity whatsoever to any legislation in the United States.