PARIS (AFP) - United States Republican presidential frontrunner Donald Trump has rung alarm bells around the world with his proclamations on foreign policy, but his targets are increasingly shrugging off his barbs.
By suggesting that Nato is "obsolete" and that Japan and South Korea should acquire nuclear weapons to rid the United States of the burden of protecting those countries, Mr Trump has called into question some of the cornerstones of US foreign policy for decades.
The property developer's comments have earned sharp rebukes from President Barack Obama and Secretary of State John Kerry.
An exasperated Mr Obama said he was "getting questions constantly from foreign leaders about some of the wackier suggestions that are being made".
Mr Obama said Mr Trump "doesn't know much about foreign policy, or nuclear policy, or the Korean Peninsula, or the world generally".
When Mr Kerry visited the Hiroshima atomic bomb memorial on April 11, he described Mr Trump's proposals to provide nuclear weapons to Japan and South Korea as an "aberration".
Professor Kazuhiro Maeshima, professor of politics at Sophia University in Tokyo, said Mr Trump's comments were "a bluff based on unrealistic views" because the US-Japan security alliance is clearly "contributing to the US national interest".
If Mr Trump became president, "it would at the very least create confusion and carries the risk of triggering a major turning point for the Japan-US alliance and Japan's overall diplomacy", Mr Maeshima said.
Although Mr Trump leads the Republican primary race, he is projected to lose an election against the likely Democratic nominee Hillary Clinton.
But the question is whether Mr Trump's campaign could cause lasting damage to America's foreign relations, or at the very least worry its allies and exacerbate strains with unfriendly nations.
For example, he caused widespread consternation when he said his "No. 1 priority" if he became president was to dismantle the carefully crafted deal between global powers and Iran on its nuclear programme.
The comments appear to have been an attempt to play to the pro-Israel lobby in the United States because Israel ferociously opposed the deal.
"When I become president, the days of treating Israel like a second-class citizen will end on day one," Mr Trump told the powerful American Israel Public Affairs Committee.
Mr Nimrod Goren, chairman of the Israeli Institute for Regional Foreign Policies (Mitvim), said that even with such overt support for the Jewish state, "when it comes to Trump there are a lot of question marks as he is not a traditional Republican politician".
He said Mr Trump - and his closest Republican rival Ted Cruz, who has also called into question the Iran deal - was actually unlikely to win votes from the pro-Israel lobby by talking tough on the issue.
"It is not by chance you don't hear about the Iran deal in the Israeli debate any more. It is considered a done deal. I don't think any people think you can reverse it," Mr Goren said.
In Iran, most people believe that if Trump somehow wins the presidency, the Washington machine will curb his ambitions, a Teheran-based academic said.
"Candidates like Mr Trump, despite their tough and hostile stances, once they take office, the body of expertise in the State Department, the Pentagon, the CIA, and the UN Security Council etc will prevent him from making just any decision he desires," Professor Nasser Hadian, professor of international relations at the University of Teheran, told AFP.
The analyst also said Mr Trump had less "credibility" than Mrs Clinton and so as president would find it hard to persuade the rest of the world to follow his lead if he tried to impose new sanctions on Iran.
Some of Mr Trump's comments - short on research but big on headline-grabbing potential - have allowed his opponents to label him unfit to be commander-in-chief.
This week, Mr Kerry swung into action again to say the United States must never again resort to torture.
Mr Trump has repeatedly said he supports the use of waterboarding, or simulated drowning, and "a hell of a lot worse" on terror suspects.
Senator Cruz argues that waterboarding does not amount to torture and that he would consider authorising it if the US faced imminent attack.
In an apparent jab at the candidates, Mr Kerry said he wanted to "remove even a scintilla of doubt or confusion that has been caused by statements that others have made in recent weeks and months".
"The United States is opposed to the use of torture in any form, at any time, by any government or non-state actor."
In Mexico meanwhile, an effigy of Mr Trump was set ablaze in Easter celebrations, showing that he has still not been forgiven for comments he made early in his campaign accusing Mexican immigrants in the United States of being criminals and rapists.