BERLIN (Reuters) - U.S. President Donald Trump’s new ambassador to Germany, Richard Grenell, warned German companies to halt activities in Iran after the U.S. leader said Washington was pulling out of the Iran nuclear deal and would reimpose sanctions. 
 
 Grenell, a long-time critic of the 2015 nuclear deal, posted the warning on Twitter just hours after arriving in Berlin and presenting his credentials to the German president. 
 
 Trump made the announcement in a televised address from the White House, in a move that will raise the risk of conflict in the Middle East, upset Germany and America’s other European allies, and unsettle global oil markets. 
 
 “US sanctions will target critical sectors of Iran’s economy,” Grenell said in his first posting on Twitter after arriving in Germany. “German companies doing business in Iran should wind down operations immediately.” 
 
 German industry reacted nervously to the U.S. announcement, warning that European companies could face U.S. fines if their Iranian business partners wound up on U.S. sanctions lists. 
 
 Grenell is starting his job in Berlin nearly 16 months after his predecessor John Emerson left the country. 
 
 A Republican foreign policy writer and avid Twitter user, Grenell was an aide to Trump’s new national security adviser, John Bolton, when Bolton was former Republican President George W. Bush’s ambassador to the United Nations. Grenell served as the U.S. spokesman at the United Nations from 2001 to 2008, and then worked as a contributor to Fox News. 
 
 The U.S. Senate confirmed Grenell on April 26, making him the highest-ranking openly gay official in the Trump administration. The next day, he joined Trump at the White House to welcome Chancellor Angela Merkel for talks that produced little movement on trade disputes or the Iran accord. 
 
 Trump had nominated Grenell in September but key Democrats help up his confirmation, citing concerns about what they called Grenell’s history of making statements insulting to women politicians on the internet and during television appearances. 
 
 Asked about such comments during his confirmation hearing, Grenell said he was trying to be funny, not insulting, and would not have made such statements while serving as a U.S. public official. ||||| Berlin (CNN) Politicians on both sides of the Atlantic have criticized US Ambassador to Germany Richard Grenell for giving an interview to far-right news platform Breitbart in which he said he wants to "empower" European conservatives. 
 
 Grenell, who took up his post last month and is a close ally of US President Donald Trump, also described Germany's NATO spending as "woeful" and criticized Chancellor Angela Merkel's immigration policy. 
 
 The ambassador has been rebuked for politicizing diplomacy at a time when US-German relations are already strained over Trump's withdrawals from the Iran deal and the Paris climate accord, along with his imposition of steel and aluminum tariffs on the European Union. 
 
 But Grenell has since insisted that his remarks have been misinterpreted. "The idea that I'd endorse candidates/parties is ridiculous," he wrote on Twitter early Monday. 
 
 Germany's foreign ministry has asked the US for clarification of Grenell's comments, according to spokesman Christofer Burger. 
 
 A State Department official, speaking on background, said, "Ambassador Grenell clarified his comments via Twitter and noted it is not US policy to endorse candidates or parties. He was making general observations in the interview." 
 
 Grenell: Austrian chancellor is 'rock star' 
 
 At a sit-down interview with Breitbart London in Berlin, Grenell said, "There are a lot of conservatives throughout Europe who have contacted me to say they are feeling there is a resurgence going on." 
 
 He added: "I absolutely want to empower other conservatives throughout Europe, other leaders. I think there is a groundswell of conservative policies that are taking hold because of the failed policies of the left." 
 
 Grenell went on to attribute this "resurgence" to the election of Trump and said that "support is massive" for conservative policies on migration as well as tax cuts and reducing bureaucracy. 
 
 He did not say whether he included Merkel -- of whom he has previously said he is a "big fan" -- as one of the conservatives he supported. But by describing Austrian Chancellor Sebastian Kurz -- a hard-right conservative who wants to clamp down on migration and support for asylum seekers -- as a "rock star" and describing himself as a "big fan," Grenell made his position clear. 
 
 In addition to criticizing Germany's NATO spending, Grenell alleged that Germany is not ready for military action -- both indirect criticisms of a leader who has been in power for 13 years -- while also attacking the Chancellor directly for the decision to allow migrants and refugees into the country in 2015. 
 
 "Donald Trump talks a lot about chain migration, and that is actually the issue here in Germany — it's chain migration," Grenell said. "Many migrants have been allowed to come in, that was the policy of Chancellor Merkel." 
 
 Sebastian Kurz became Chancellor of Austria in December. 
 
 'Grenell isn't behaving like a diplomat' 
 
 US Senator Chris Murphy said on Twitter that he had raised concerns with Grenell in the past about politicizing the ambassador post. "He personally assured me that once he became Ambassador he would stay out of politics," Murphy wrote. "This interview is awful - Ambassadors aren't supposed to 'empower' any political party overseas." 
 
 When I raised concerns to Grenell about politicizing this post, he personally assured me that once he became Ambassador he would stay out of politics. This interview is awful - Ambassadors aren't supposed to "empower" any political party overseas. https://t.co/i8oOhqEk5k — Chris Murphy (@ChrisMurphyCT) June 3, 2018 
 
 Metin Hakverdi, Social Democrat member of the German parliament, told The Guardian he agreed with Murphy and said he was "irritated" by Grenell's comments. 
 
 "In the past, Germany was fortunate to have had great US ambassadors who built bridges and did not do party politics," he said. 
 
 Former Social Democrat leader Martin Schulz told Germany's national news agency DPA, "Grenell isn't behaving like a diplomat, but instead like a right-wing colonial officer. Ambassadors are representatives of their states and not of political movements." 
 
 The choice of platform is potentially provocative too. On at least two occasions, Breitbart's Germany reporting has been exposed as misleading or even wholly false. 
 
 A report that a group of Muslim migrants had set fire to Germany's oldest church on New Year's Eve 2016 was later debunked by Dortmund's police. The church in question was not set on fire, nor was it Germany's oldest. 
 
 Last summer, Breitbart was forced to issue an apology after using a picture of German soccer player Lukas Podolski to illustrate a story about migrants traveling to Spain. 
 
 It is the second time in less than a week that a US ambassador has made public comments considered to be partisan. In an interview with The Times of Israel last week, David Friedman, US Ambassador to Israel, criticized the Democratic Party for failing to "create support within their constituency for Israel at the same levels that the Republicans have." 
 
 Former Congressman Ron Klein, chair of the Jewish Democratic Council of America, described the remarks in a statement as "truly unprecedented" and said that such "partisan behavior is damaging to our national interests and must stop immediately." 
 
 Retired US Ambassador Ronald Neumann told CNN that American diplomats normally stay out of anything that directly touches on particular political parties. 
 
 "This is not protocol or political correctness, but common sense," said Neumann, now the president of the American Academy of Diplomacy. "If the group you favor loses, the resulting government is not likely to look kindly on your interference." 
 
 Referring to Russian President Vladimir Putin, Neumann, a former ambassador to Afghanistan and Bahrain, said that the US "would be offended if Mr. Putin spoke publicly about his preference for a US political party. The reaction of others is the same." ||||| U.S. Ambassador to Germany Richard Grenell, left, and German President Frank-Walter Steinmeier | Odd Andersen/AFP via Getty Images German politicians call on US to withdraw ambassador Richard Grenell under fire for saying he’ll seek to ’empower’ anti-establishment parties across Europe. 
 
 German politicians are calling for U.S. Ambassador to Germany Richard Grenell to be recalled, following a controversial interview in which the diplomat claims he is seeking to boost anti-establishment parties across Europe. 
 
 “What this man is doing is unprecedented in international diplomacy,” former Social Democrat leader Martin Schulz told German daily Tagesschau on Tuesday. 
 
 “If a German ambassador in Washington said, ‘I’m here to strengthen the Democratic Party,’ he would be thrown out immediately,” he added. 
 
 Schulz accused Grenell of acting as a representative of a political movement instead of maintaining a neutral stance toward his host country, and on Monday described him as a “far-right colonial official.” 
 
 In an interview published late Sunday, Grenell told far-right news site Breitbart he “absolutely wants to empower other conservatives throughout Europe” and encourage people to rise up against “elites.” 
 
 Grenell, who took office less than a month ago, has been asked to clarify his comments during his inaugural visit to the foreign office on Wednesday, according to Tagesschau. 
 
 Sahra Wagenknecht, the leader of Germany’s left-wing Die Linke, has also called for Grenell to be withdrawn. 
 
 “If the German government takes our country’s democratic sovereignty seriously, it should not invite Grenell to coffee, but expel him immediately,” Wagenknecht said. 
 
 Jürgen Hardt, the foreign policy spokesperson for Angela Merkel’s conservative bloc, responded to the comments by saying: “It is not my place to tell the new U.S. ambassador how to exercise his functions or which media outlets to speak to.” 
 
 He added that he hoped Grenell would “invest all of his energy into supporting close coordination” on a number of urgent transatlantic issues, including the Middle East and trade policy. 
 
 “The idea that I’d endorse candidates/parties is ridiculous,” Grenell tweeted in response to the blowback over his comments. “I stand by my comments that we are experiencing an awakening from the silent majority — those who reject the elites & their bubble. Led by Trump.” 
 
 Grenell is due to host Austrian Chancellor Sebastian Kurz — a staunch critic of Angela Merkel’s migration policy whom Grenell called a “rockstar” of European politics in his Breitbart interview — for a meal on June 13, German media reported.
– Richard Grenell's first day on the job may not have gone exactly how he imagined it. The brand new US ambassador to Germany arrived in Berlin on Tuesday, and in the span of little more than an hour, three things occurred: Grenell handed his credentials to Germany's president, President Trump announced the end of America's participation in the Iran nuclear deal, and Grenell raised some German ire. It's all due to this tweet, made shortly after Trump spoke: "As @realDonaldTrump said, US sanctions will target critical sectors of Iran’s economy. German companies doing business in Iran should wind down operations immediately." Reuters notes Grenell has himself long-opposed the nuclear deal. That sentiment aligns with the White House's—indeed, Grenell, a former Fox News contributor who Page Six notes had an "A-list" going away bash, subsequently tweeted that he directly lifted the language from documentation provided to him by the administration. But the Washington Post observes that "the timing and tone struck some German politicians, journalists and businessmen as offensive and inappropriate." It characterizes the tweet as coming off as a threat and rounds up plenty of reaction, including this from the leader of the country's Social Democratic party: "It’s not my task to teach people about the fine art of diplomacy, especially not the US ambassador. But he does appear to need some tutoring." Grenell, the administration's top-ranking openly gay official, fills an ambassadorship that has been empty for 16 months.