But it was more than that, Mr. Schröder said. “I had been chancellor. I couldn’t go back to being a lawyer dealing with rental contracts. I needed a project,” he said. “Something I knew how to do and where I could serve German interests.”
When Mr. Putin called Mr. Schröder on his cellphone the night of Dec. 9, 2005, he accepted the offer.
Many in Germany were appalled. No chancellor before him had taken a job in a company controlled by a foreign country, let alone one that had benefited from their support in office.
But the pipeline project itself remained uncontroversial.
“The next government continued with it seamlessly,” Mr. Schröder recalled. “Nobody in the first Merkel government said a word against it. No one!”
Mr. Ischinger, who was Mr. Schröder’s ambassador to the United States and later ran the Munich Security Conference, concurred.
“You can’t blame Schröder for Nord Stream 1,” Mr. Ischinger said. “Most German politicians, whether in government or in opposition, did not critically question this. No one asked whether we were laying the foundation for getting ourselves into an unhealthy dependence.”
Ms. Merkel, through a spokesperson, declined to comment for this article.
Nord Stream 1 took six years to plan and build. In 2011, Mr. Schröder attended both opening ceremonies — one on the Russian end, in Vyborg, along with Mr. Putin, Russia’s prime minister at the time, and the other on the German end, in Lubmin, on the Baltic Sea, along with Ms. Merkel and Mr. Putin’s trusted ally, Dmitri A. Medvedev, Russia’s president at the time.