US President Barack Obama acknowledged Tuesday that no matter how much pressure America applies to the parties in the Middle East conflict, peace may not be achieved.

He also said that the US cannot “impose solutions” in all conflicts and urged Israel and other non-signatories of the Nuclear Non-Proliferation Treaty to join, during a press conference capping the two-day Nuclear Security Summit he convened.

Speaking of Middle East peace, Obama said that “even if we apply all our political capital to that issue, the Israeli people through their government and the Palestinian people through the Palestinian Authority as well as other Arab states may say to themselves, we are not prepared to resolve these issues no matter how much pressure the United States brings to bear.”

He added, “The truth is that in some of these conflicts, the United States cannot impose solutions, unless the participants in these conflicts are willing to break out of old patterns of antagonism.”

Quoting former US secretary of state James Baker, who served under George H.W. Bush, Obama said, “We can’t want it more than they do.”

But he continued by saying that he would keep on trying even though progress would “take time,” stressing that “what we can make sure is that we are constantly present, constantly engaged.”

Asked whether America’s nuclear policy smacked of hypocrisy because it doesn’t take Israel to task for not joining the NPT despite the widespread belief that it has an undeclared nuclear arsenal, Obama said that US policy has long been to encourage all countries to sign the NPT.

“Whether we’re talking about Israel or any other country, we think that becoming part of the NPT is important,” he said.