According to the expert, German decisionmakers will act like US President Donald Trump.
"They will say 'we don't agree with this law, but we can't do anything against it, because our partners within the EU want the same as the US,'" the analyst noted.
In Rahr's opinion, the US has very strong levers of pressure in its hands. Washington is capable of literally forcing all German firms and factories to play its game.
"These firms are located on US territory and they can become subject to severe penalties if they contradict the Americans. Therefore, unfortunately, the management of these firms will have to think what is more important for them in the long run: business with Russia or business with the US," Rahr argued.
The expert also stressed that he fears a new propaganda media campaign to justify the policy of new restrictions against Russia. According to him, mainstream media are likely to release lots of reports labelling Russia as a "great aggressor."
"I'm afraid that we will again enter a new spiral of confrontation," Rahr concluded.
The law also limits the US president's ability to ease any sanctions on Russia by requiring Congress's approval to lift any restrictions.
Earlier on Thursday, Kremlin spokesman Dmitry Peskov said that Russia would defend its interests amid new US sanctions.
Last week, the Russian Foreign Ministry described the new sanctions as "absolutely illegitimate" and responded with countermeasures, suspending the use of all US Embassy warehouses and its compound in Moscow. Russia also mandated that the US cut the size of its diplomatic staff in Russia by 755 people by September 1.