"The letter includes condolences for the terrorist attack in Moscow on March 22 and for those affected by the recent floods affecting several regions of Russia," Defense Department spokesman Lorenz Frischknecht was quoted as saying by the news portal.
The letter was an attempt to call for a dialogue in tough times, he said. In the letter Amherd said that respect for international law and the principles enshrined in the UN Charter should be "the compass for achieving peace and prosperity," as quoted in the report.
At the same time, Frischknecht noted that the letter was not a congratulation to Putin on his reelection as the Russian president.
Russian regions located in the Ural Mountains and Siberia have been grappling for weeks with strong floods sparked by rapid snowmelt and rising water levels in rivers. The regions of Kurgan, Orenburg and Tyumen have declared a state of emergency.
On March 22, several armed men broke into the Crocus City Hall concert venue near Moscow and started shooting indiscriminately at concert-goers. They also started a fire in one of the auditoriums, which was full of people ahead of a concert. The attack left 145 people dead and many more injured. The four main suspects in the case tried to flee the scene in a car but were detained and charged with terrorism.