Republican frontrunner Donald Trump has declared that his first foreign policy priority if he becomes US president would be to dismantle the Iran nuclear deal and what he said was Iran's global terror network.
"My number one priority is to dismantle the disastrous deal with Iran," the Republican frontrunner told the conference of the US pro-Israel lobby AIPAC in Washington.
"I have been in business a long time. I know deal making. And let me tell you, this deal is catastrophic. For America, for Israel and for the whole of the Middle East."
Mr Trump - unusually, speaking from a teleprompter - did not receive as warm a reception at the AIPAC event as he does in his bombastic campaign rallies, but the crowd warmed to his attacks on Iran and US President Barack Obama.
"With President Obama in his final year, he may be the worst thing to ever happen to Israel, believe me. Believe me," he said to applause.
"We will totally dismantle Iran's global terror network which is big and powerful but not powerful like us," he vowed, accusing the current White House of pressuring US allies while rewarding enemies like Iran.
Mr Trump has also said he would recognise Jerusalem as Israel's capital and move the US embassy there.
Israel regards the divided city as its capital but many countries, including its ally the United States, have resisted moving their missions there while its status and borders are still a matter of dispute.
Palestinians also see the city - which is holy to Jews, Christians and Muslims - as their future capital, and any final peace deal between the peoples would have to include an agreement on sovereignty.
Mr Trump has previously suggested he would be neutral in the Israeli-Palestinian dispute.
But shortly before addressing AIPAC, he told CNN: "There's nobody more pro-Israel than I am. We have to protect Israel. Israel is so important to us."
And, asked whether he would recognise Jerusalem as Israel's capital and move the US embassy from Tel Aviv to Washington, Mr Trump replied: "Yes, I would."
"The fact is I would like to see it moved, I would like to see it in Jerusalem," he said.
In 1967, with Israel under attack from Arab armies, Israeli forces occupied East Jerusalem, driving back Jordanian troops and taking control of some areas with majority Arab populations.
Palestinians still campaign for an Israeli withdrawal from the east of the city - and Jordan still has administrative responsibility for the holy sites on the Temple Mount area of the Old City.
Trump questions financial backing for NATO
Mr Trump also said the US should significantly cut spending on the North Atlantic Treaty Organisation (NATO).
Mr Trump, whose world views have been rebuked by a section of the Republican establishment, made the comments as he unveiled a partial list of foreign policy advisors who are relatively little known.
"We are paying disproportionately (for NATO). It's too much and frankly it's a different world than it was when we originally conceived of the idea," Mr Trump said.
"We have to reconsider. Keep NATO, but maybe we have to pay a lot less toward NATO itself."
The US is the biggest contributor to NATO, and US officials have long been critical of its European allies for not spending more.
NATO is planning its biggest build-up in eastern Europe since the Cold War to deter Russia, helped by an increase in planned US spending.
