WASHINGTON — In a major blow to the Israeli government’s efforts to isolate the Hamas-backed Palestinian unity government, the US said Monday it would work with the new West Bank-Gaza leadership, which was sworn in on Monday afternoon, and would maintain its aid to the Palestinian Authority. It said it would be “watching closely” to ensure the new government respects the principles of non-violence.

The US position is in conflict with the official stance in Jerusalem, which outright rejects the new Palestinian leadership because Hamas remains committed to destroying Israel and is a designated terrorist organization in Israel, the US and the EU.

State Department spokeswoman Jen Psaki said on Monday that Washington believes Palestinian Authority President Mahmoud Abbas has “formed an interim technocratic government…that does not include members affiliated with Hamas.”

“With what we know now, we will work with this government,” Psaki said. She did, however, warn that the US “will continue to evaluate the composition and policies of the new government and if needed we’ll modify our approach.” She later added that the administration would be “watching carefully to make sure” that the unity government upholds the principles that serve as preconditions for continuing US aid to the Palestinian Authority.

Reached for comment, Israel’s foreign ministry declined to respond to the statements from Washington. But the US move was a major surprise; sources in Washington had been quoted in Israel in recent days saying the US would not immediately recognize the new PA government.

As recently as Sunday, Secretary of State John Kerry called Abbas and “expressed concern about Hamas’s role in any such government and the importance that the new government commit to the principles of nonviolence, recognition of the state of Israel and acceptance of previous agreements with it,” Psaki had said in remarks Sunday.

Earlier Monday, Kerry discussed the recent developments in a phone call with Prime Minister Benjamin Netanyahu. State Department officials would not confirm the tone of the conversation, or comment on whether the US administration’s announcement had come as a surprise to the Israeli government.

But asked if Israel would agree to return to the negotiating table after it suspended the talks in April, Psaki said that would be up to the Israeli government to decide.

“It is ultimately up to the parties … to make the difficult decisions about coming to the negotiating table,” she said. “So we will see. We are not in a position to make a prediction at this point.”

Psaki said that the United States is open to the current plan set out by the interim unity government, according to which long-delayed elections in the Palestinian Authority will be held in six months’ time.

“As a matter of principle we support democratic free and fair elections,” Psaki said, but added that “it is too early to speculate as to what the outcome will be and we will let events proceed.”

The State Department spokeswoman commented that although the US continues to expect Abbas to uphold his commitment to maintaining security coordination with Israel, Hamas’s support for the current government did not change the American perspective on culpability for rocket attacks launched toward Israeli targets from the Hamas-controlled Gaza Strip.

“We expect the PA to do everything in its power to prevent attacks from Gaza, but we understand that [the] Gaza Strip is under the control of Hamas,” Psaki explained.

Earlier in the day, Abbas swore in 17 ministers in a new technocratic government meant to steer the PA toward elections within six months.

The Israeli cabinet, meanwhile, said on Monday it would hold the new government responsible for any rockets fired at Israel from Gaza.

In a decision approved at a special meeting of the Ministerial Committee for National Security Affairs, Netanyahu and eight top ministers said they would boycott the new government and form a team to “examine courses of action” in light of the new Palestinian unity government.

Abbas swore in the ministers of the new unity government Monday afternoon after Gaza’s Hamas rulers and Abbas’s Fatah resolved a last-minute disagreement over a key government ministry.

He hailed the “end” of Palestinian division, saying: “Today, with the formation of a national consensus government, we announce the end of a Palestinian division that has greatly damaged our national case.”

Abbas has pledged that the new administration will abide by the principles laid down by the Middle East peace Quartet that call for recognizing Israel, rejecting violence and abiding by all existing agreements, though Hamas has yet to ratify those conditions.

Elhanan Miller and other Times of Israel staff contributed to this report.