Vice President Mike Pence warned European countries on Tuesday that the Trump administration plans to withdraw the U.S. from a nuclear agreement with Iran unless the deal undergoes significant changes.

“We are sending a signal to our European allies that the time has come for changes in the Iran nuclear deal," Pence said during an appearance with Israeli President Reuven Rivlin in Jerusalem on Tuesday.

“If our allies won’t join us, President Trump has made clear we will withdraw from the Iran nuclear deal immediately,” Pence said. “But we hope, we hope in the months ahead to be able to strengthen it.”

Pence said the changes to the deal, known formally as the Joint Comprehensive Plan of Action, must include the removal of "sunset provisions," which allow certain restrictions on Iran's nuclear capability to expire after a certain period of time, and the ability to impose "punitive sanctions" on Iran "for many years to come."

Trump has described the JCPOA as an "embarrassment" to the U.S. and vowed as a candidate to tear up the deal. Although he declared the agreement counter to American national security interests in October — a move that gave Congress responsibility for reviewing the JCPOA — he has yet to decertify the deal completely, or to revive the sanctions that the Obama administration suspended in exchange for limits on Iran's production of nuclear material.

The Israeli government has applauded the Trump administration's tough stance against Iran. However, a number of European allies that also signed onto the JCPOA have criticized Trump for threatening the future of the deal, which they say adequately prevents Iran from obtaining a nuclear weapon in the near future.

Trump administration officials, particularly U.S. Ambassador to the United Nations Nikki Haley, have argued that the previous administration overlooked Iran's provocative behavior in areas that go well beyond nuclear production in order to secure a deal.