"Today is a good day, or maybe even a historic one for all those who wish for a peaceful conflict resolution, and it is a wonderful moment for me, personally," said Germany's foreign minister, Frank-Walter Steinmeier, in Vienna on Tuesday.

His relief was obvious - but so, too, was his exhaustion after marathon negotiations that went on far longer than planned.

"I had said that June 30 would be a long day, but I didn't expect it to go on for 348 hours," Steinmeier said, alluding to the fact that the agreement was meant to have been wrapped up last Tuesday rather than this.

The day could be seen as historic because it proved that dialogue and perseverance could solve major international conflicts "even when mistrust and initial hostility seemed overwhelming," said Steinmeier, pointing out that, after more than a decade, a conflict which had almost pushed the world to the brink of a military clash had now been settled.

Consensus with a message

Steinmeier is convinced that the nuclear agreement with Iran conveys a positive message to the entire Middle East. "This agreement may send a signal of hope to resist the powers of chaos in the Middle East," he stated.

Steinmeier also rejected Israel's criticism of the international treaty with Iran. "I am sure that we can satisfy Israel with this treaty," he said.

The deputy chairman of the German Christian Democrat (CDU) parliamentary group, Franz Josef Jung, however, emphasized the importance of strict controls.

"It is important that compliance with the agreement can be reviewed at any time," said Jung, a former German defense minister. "This verifiability is essential not only for the security of Israel, but that of the entire region." Jung also spoke of a "historic outcome" – if the agreement worked.

Opposition approval

The foreign policy experts in Germany's opposition parties also embraced the resolution of the dispute over Iran's nuclear program as a triumph of diplomacy.

The foreign policy expert of the Left party, Jan van Aken, especially thanked US President Barack Obama and his Iranian counterpart Hassan Rouhani, who had "broken with the senseless, confrontational policies of their predecessors." The agreement was "a major step towards more stability in the Middle East," he said.

The Greens' expert on foreign policy, Omid Nouripour, called the agreement a "victory of reason." The negotiators had shown "that political will and persistent diplomacy can resolve long-standing conflicts peacefully." At the same time, Nouripour and van Aken also criticized the poor human rights situation in Iran as standing in the way of fully normalized relations.

Business opportunity

The nuclear agreement also met with great approval and relief from the German business world.

Ulrich Grillo, the president of the national industrial federation BDI, described the deal as an "important contribution to stability and security in the entire region."

With its approximately 80 million inhabitants, Iran was a market of significant size, said Grillo. He noted that the country's industrial infrastructure was in great need of modernization, with the Iranian oil industry in particular opening up market chances for German mechanical and plant engineering.

"The automobile industry, the chemical industry, the healthcare sector and the expansion of renewable energies offer German industry many opportunities," Grillo said.

Anton Börner, chairman of leading German trade organization BGA, also spoke of a "historic event."

Economy minister to make Tehran visit

In 2014, Germany sold goods to Iran worth nearly 2.4 billion euros ($2.64 billion). The elimination of sanctions could quickly change the situation.

"Within two years, our exports there can double to around five billion euros," said Volker Treier, foreign trade chief of the Association of German Chambers of Commerce and Industry (DIHK). "If everything goes well, we could exceed the 10 billion mark for exports in three or four years."

The German government is aware of the opportunities that will arise when the trade embargo is lifted. German Economy Minister Sigmar Gabriel will be traveling to Iran with high-ranking business leaders on Sunday and staying until Tuesday, according to the DPA news agency. Meetings in Tehran and Isfahan are reportedly planned until Tuesday.