German interference in the U.S. political system as means of countering President Trump’s foreign policy agenda has sparked sharp criticism from Republican senators.

There has been no shortage of conflict between Trump and German Chancellor Angela Merkel, who have locked horns over trade, Iran, Israel's capital Jerusalem and NATO.

German politicians have lashed out at the Trump administration over the past few weeks, criticizing, in particular, the president’s decision to withdraw the U.S. from the Iran nuclear deal.

Heiko Maas, Germany’s Social Democratic foreign minister and a passionate defender of the Iran deal, on Wednesday said: "America is bigger than the White House. Trump will not change that, either. He can tweet as much as he wants."

In a recent interview with German magazine Der Spiegel, Maas’ Social Democratic colleague, Niels Annen, called for direct intervention in U.S. politics beyond the White House, urging the explicit lobbying of governors, congressmen and senators as a means of benefiting German trade policy.

Prominent party members from Angela Merkel’s own Christian Democratic Union party have also attacked Trump.

Friedrich Merz, a former leader of Merkel’s coalition in the German parliament who is now chairman of the Atlantic Bridge, an NGO devoted to promoting German-American understanding, told the Welt am Sonntag paper: “We Europeans must redefine our role in this world, at least in our minds, without the United States.”

Merz also called for intervention in U.S. politics, saying there is a need to “intensify the dialogue with those social and political groups and institutions in America that do not follow the battle cry ‘America First’ and who, like us Europeans, feel a common and mutual responsibility for an open and free society.”

The attacks come after Richard Grenell, the U.S. Ambassador to Germany, said in an interview with Breitbart last month that he wants to “empower other conservatives throughout Europe.”

Grenell, a former Fox News contributor and a fierce opponent of Iran's bellicose policies, has urged Germany to wind down its business with Iran and bar Iran's Mahan Air from entering German airspace.

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In a meeting last month with the American Israel Public Affairs Committee, Grenell revealed: “We know that Mahan Air has been used by the Iranian Revolutionary Guard Corps [IRGC] as a mode of transport for weapons, resources and fighters, so we’re asking our allies to help us put a stop to it.”

In the wake of the German meddling, Senator Ted Cruz, R-Texas, told Fox News it was “distressing” that some German politicians are straining relations with America to maintain ties with that kind of [Iran] regime.

“It is in the interest of all of our allies to comply with the American sanctions against Iran, including and especially those which were passed into law by successive American Congresses and have been affirmed by successive American presidents,” Cruz said. “In recent weeks, the Ayatollahs have been caught trying to conduct terrorism across Europe and reportedly to launch cyberattacks against us and our allies."

Cruz added: "Iran’s top political and military figures have threatened to prevent shipping through the Gulf, and just this week President Rouhani threatened the West with the ‘mother of all wars.’"

Senator Marco Rubio, R-Fla., told Fox News: “I hope Germany and our other allies in Europe will ultimately stand on the right side of history, and support the re-imposition of sanctions against Iran. In addition to being the biggest state sponsor of terrorism and a nuclear proliferator, the Iranian regime is directly complicit in the Syrian tragedy—the world’s worst humanitarian crisis since World War II.”

Senators Cruz and Rubio, along with eight additional Republican senators, sent a letter on Thursday to the ambassadors of Germany, France and the United Kingdom, urging their governments to not evade or subvert US sanctions that will be re-imposed on Iran.

In the letter obtained by FoxNews.com, the senators stated to the major European powers: "We write to urge you to comply with all American sanctions but also to emphasize we would find it particularly troubling if you sought to evade or undermine American statutes," adding that "These laws were passed by Congress, signed by President Obama and will be enforced by President Trump."

I hope Germany and our other allies in Europe will ultimately stand on the right side of history, and support the re-imposition of sanctions against Iran — Senator Marco Rubio, R-Fla.

The letter added: "Any attempt to evade or subvert them could well prompt congressional action, in coordination with other elements of the U.S. government, to ensure their integrity."

TRUMP IS RIGHT - NATO IS OBSOLETE, AND HE'S DELIVERING THAT MESSAGE LOUD AND CLEAR

When asked about the criticism of Senators Rubio and Cruz, a German foreign ministry spokesperson reiterated a comment from Maas: "Regardless of whom President Trump describes as a foe, I do not see the U.S. as an opponent, but rather as our most important partner and ally outside the E.U."

Iran, North Korea, Syria and Pakistan are making efforts to expand their conventional weapons arsenal through the production of weapons of mass destruction — Bavarian intelligence agency

The foreign ministry spokesperson wrote that Maas has previously said regarding Iran: "Let me be clear: this is not a matter of people having different attitudes towards Iran. Iran and its ballistic missile program, the role it is playing in the region, particularly what it is up to in Syria – all of this is anything but acceptable. But the point is that getting rid of the framework of security that the [nuclear deal] represents wouldn’t help; in fact, it would make it much harder to address those problems successfully."

The Merkel administration has gone to great lengths to promote the Iranian nuclear deal that aims to curb Iran's nuclear weapons ambitions.

Yet a new batch of state intelligence reports have contradicted Merkel and her coalition government’s views about the effectiveness of the Iran deal.

The state of Bavaria's intelligence report concluded that Iran's regime is working to turn its conventional military weapons into a system for weapons of mass destruction.

“Iran, North Korea, Syria and Pakistan are making efforts to expand their conventional weapons arsenal through the production of weapons of mass destruction,” wrote the Bavarian intelligence agency - the rough equivalent of the FBI.

Trump has singled out Germany for its trade surplus with the U.S, which had a whopping $64 billion trade surplus advantage over America in 2017.

The president has bitterly complained about German luxury cars flooding U.S. markets at the expense of American automobiles.

Trump's hard-charging style of negotiating influenced a change in Germany's defense security behavior at the July NATO conference in Brussels.

Trump also went on the offensive noting Germany was "totally controlled by Russia" because Europe's wealthiest country is dependent on natural gas from Russia.