Washington, March 13 (RHC)-- The German foreign minister has criticized U.S. Republican senators for signing a controversial letter to Iran, expressing concern that such moves could seriously undermine Iran’s confidence in the ongoing nuclear talks with global powers.

“This is not just an issue of American domestic politics, but it affects the negotiations we are holding in Geneva,” Frank-Walter Steinmeier said on Thursday, referring to the letter signed by 47 senators. He expressed hope that the letter of 47 senators does not cause “any disturbance in the negotiations” under way between Iran and six world powers for a permanent accord.

In an unexpected move on Monday, the Republicans issued a desperate warning to the Iranian officials on the validity of a potential nuclear deal, describing such an agreement as “nothing more than an executive agreement” which could be canceled by the next US president “by a stroke of a pen.”

The letter raised huge controversy among top U.S. government officials and notable peace activists in the country condemning the warning as a pure hawkish statement. The move has been also met with anger by other parties to the negotiations with Iran, namely Russia, China, the United Kingdom, France and Germany, which coupled with the U.S., are known as the P5+1 group.