Israeli Prime Minister Benjamin Netanyahu meets with British Prime Minister Theresa May in London Wednesday, concluding the final leg of a three-day European tour aimed at persuading European leaders to alter the international nuclear agreement with Iran.

Netanyahu began his three-day European tour Monday in Germany, where he warned Chancellor Angela Merkel Iranian meddling in the Middle East could spark massive new refugee flows to Europe. In France Tuesday, the Israeli leader said his interest is “making sure Iran doesn’t have nuclear weapons.”

“I’ve been very consistent about my opposition to this nuclear deal, because I said you cannot divorce this from Iran’s aggression in the region,” Netanyahu told a joint news conference with French President Emmanuel Macron Tuesday.

Macron said France will continue to work with the Joint Comprehensive Plan of Action (JCPOA), which it considers the best way to control Iran’s nuclear activity.

“The JCPOA is not sufficient, and I absolutely agree, but still, it’s better than what we had before.” Macron said he doesn’t see how exiting the nuclear deal would help improve regional stability.

Britain, France and Germany agreed to the deal with Iran in 2015 along with Russia, China and the United States. 

U.S. President Donald Trump announced last month the United States was pulling out of what he called a “horrible, one-sided deal,” while saying he wants additional restrictions on Iran’s ballistic missile program and what he called its “destabilizing activities in the Middle East.”

The other signatories have expressed a desire to keep the nuclear deal in place, saying it is working. Britain, France and Germany have suggested addressing other concerns about Iran through a supplemental agreement.

Like Trump, Netanyahu has been a fierce critic of the deal, saying the agreement left Iran with the potential to quickly develop a nuclear weapon when the terms expire.

Iran, which won sanctions relief in exchange for limiting its nuclear program, has said repeatedly its nuclear activity was solely peaceful in nature.

Iranian Foreign Minister Mohammad Javad Zarif said Sunday the U.S. decision to withdraw from the agreement was illegal and he urged the other signatories not to follow suit.

State-run Iranian media said Zarif sent a letter to the foreign ministers of the remaining nations. He asked them to “make up” for the Iranian losses brought on by the U.S. withdrawal if they want to save the deal.

Zarif called the 2015 nuclear agreement the result of “accurate, sensitive and balanced multilateral talks.”

“The illegal withdrawal of the U.S. government…especially bullying methods used by this government to bring other governments in line, has discredited the rule of law while challenging the principles of the U.N. Charter and efficiency of international bodies,” Zarif wrote.