JERUSALEM (AFP) – Israeli Prime Minister Benjamin Netanyahu suffered a major defeat in failing to stop a nuclear deal with Iran but he remains as defiant as ever even at the risk of further isolation.

While the world’s major powers welcomed the deal finalised with Iran on Tuesday as a historic moment capable of setting relations with the Islamic republic on a new path, Netanyahu harshly condemned it.

For the 65-year-old savvy right-wing prime minister, the agreement was a “stunning, historic mistake”.

He stressed Israel would not be bound by the deal and – again signalling that military force was not off the table – said the country would “always defend ourselves”.

On Wednesday, he declared the agreement was “not the end of the story”.

“We are going to continue to denounce the danger in reaching an agreement with a dictatorial regime,” he said.

Netanyahu argues the deal will fail to block Iran’s path to nuclear weapons that could be used to target the Jewish State, and says the lifting of sanctions will allow it to further support proxy militants in the Middle East.

While he has angered US President Barack Obama by appearing before Congress in Washington to argue against the agreement, there is wide support for Netanyahu’s stand among his political allies in Israel.

The Opposition has also denounced the deal, while at the same time criticising Netanyahu for deteriorating relations with the United States, the country’s most important ally.

“Netanyahu wants to go down in history as practically the only person to warn to the very end against the dangers of a nuclear Iran,” a senior Israeli official told AFP on condition of anonymity.

“He knows in advance that it is a losing battle in the short-term, but he cannot stand idly by.”

His focus now is likely to turn to the US Congress, which has 60 days to review the deal. Netanyahu has allies there, particularly among Republicans, but their chances of sinking the agreement appear unlikely for now.

Even if the deal is voted down in Congress, Obama can veto the move. Congress can only override the veto with a two-thirds vote.

Obama has sought to reassure Netanyahu, telling him in a telephone conversation on Tuesday night that the agreement was in Israel’s “national security interest”.

He also announced US Defence Secretary Ashton Carter would visit Israel next week.

British Foreign Secretary Philip Hammond said he was heading to Israel Wednesday night to explain the deal in person, with a meeting set with Netanyahu for Thursday.

Israel is believed to be the only country in the Middle East with atomic bombs, although it has never confirmed it.