US Foreign Minister Anthony Blinken said on Monday he was “deeply concerned” by Israel’s decision to legalize nine settlements in the occupied West Bank and advance plans to build thousands of new homes on existing ones.

“We are deeply concerned about Israel’s decision yesterday to advance the construction of up to 10,000 housing units and to retroactively begin the process of legalizing nine settlements in the West Bank previously considered illegal under Israeli law,” Mr. Blinken noted in a press release that released by his State Department services.

“Like previous administrations, Democratic and Republican, we strongly oppose such unilateral measures, which escalate tensions and undermine the prospects for achieving a negotiated two-state solution,” Mr. Blinken added.

The Israeli government announced the measures on Sunday, although during Mr. Blinken’s recent visit to the region, the US secretary specifically warned against resuming settlement activity in the occupied territories to de-escalate tensions.

“Anything that moves us away from the vision of two states for two peoples is detrimental to Israel’s long-term security,” the US Secretary of State emphasized.

Benjamin Netanyahu’s government presented the decision in response to a series of attacks by Palestinians in East Jerusalem that have killed three people since Friday.

The nine settlements were until now classified as illegal under Israeli law, since they were built without government permission. For the UN, however, any initiative to settle Jewish settlers in the occupied Palestinian territories is illegal under international law, regardless of whether permission is given or not.

Israel captured the West Bank in the Arab-Israeli war of June 1967. More than 475,000 Israeli settlers live in settlements in the West Bank—beyond East Jerusalem—among 2.8 million Palestinians.