The German government has warned the US against withdrawing from the Iran nuclear agreement. US President Donald Trump is expected to decertify Tehran's compliance with the 2015 deal in a White House speech at 12:45 p.m. (16:45 UTC) on Friday.

"We believe this agreement is an important instrument to prevent a nuclear-armed Iran," German government spokesman Steffen Seibert said on Friday.

"If ... an important country like the United States comes to a different conclusion as appears to be the case, we will work even harder with other partners to maintain this cohesion," he said.

Transatlantic split at stake

German Foreign Minister Sigmar Gabriel on Thursday said that any move by US President Donald Trump's administration to withdraw from the Iran nuclear deal would drive a wedge between Europe and the US.

"It's imperative that Europe sticks together on this issue," Gabriel told Germany's RND newspaper group. "We also have to tell the Americans that their behavior on the Iran issue will drive us Europeans into a common position with Russia and China against the USA."

Read more: What is the Iran nuclear deal?

Despite countless warnings from global leaders and even from within his own administration, Trump is expected on Friday to unveil a new strategy on confronting Iran, which would include "de-certifying" Iran's compliance to the nuclear accord. The deal, which was reached in 2015 between Iran and international powers, saw international sanctions related to Iran's nuclear program lifted in exchange for Tehran dismantling the program.

The United Nations nuclear watchdog has repeatedly certified that Iran has been adhering to the restrictions imposed by the accord. Trump, however, has decried Iran for violating "the spirit" of the deal, first by backing Syrian President Bashar al-Assad and then by test firing its newly-developed non-nuclear ballistic missiles.

"The big drama is that the Iran agreement could turn out to be a pawn in American domestic politics," Gabriel said. Washington wants the agreement to ensure that Iran ceases to fuel conflicts such as in Syria, Iraq, or Yemen. But Gabriel said this could not be a condition for Iran to remain free of nuclear weapons.

Trump has until Sunday to inform Congress whether he believes Iran is complying with the nuclear agreement. Should Trump de-certify Tehran's compliance, Congress will have to decide within 60 days what new sanctions to impose on Iran.

A 'hot crisis' region

Several EU and US officials have warned that Trump's refusal to certify the deal could leave the US diplomatically isolated. Germany has historically close economic and business ties with Russia, although those have soured in recent years following Russia's annexation of Crimea. Berlin, and Gabriel in particular, have also been working to boost relations with China.

Read more: Berlin sees opportunity to strengthen trade ties with China

"A denunciation of the Iran agreement would turn the Middle East into a hot crisis region," Gabriel warned, adding that if Iran were to resume developing nuclear weapons, then "the immediate danger of a new war" would return, with Israel potentially involved.

"It would be a devastating signal for nuclear disarmament," Gabriel said. "Some states might see the failure of the Iran agreement as a signal to arm themselves with nuclear weapons as soon as possible."

Gabriel's potential successor weighs in

Gabriel is expected to stand down from his post in the coming months, after his Social Democratic Party (SPD) announced that it would go into opposition after finishing second behind Chancellor Angela Merkel's Christian Democrats in last month's federal election.

One of the candidates widely tipped to succeed him as top diplomat, Green party leader Cem Özdemir, also warned on Twitter against a nuclear arms race and said that Saudi Arabia could even become a new nuclear power in the region.

amp, dm/bk (Reuters, dpa, AFP)