

The thretened tariffs arent on Russia, since as you point out there is little trade between USA and Russia it would be innefective in swaying the kremlin. These tariffs are instead being put on countries that trade with Russia like China, India, Brazil etc, with the hope that those countries will put pressure on Russia by proxy.



By Wikipedias count there are presently 51 on-going national emergencies in USA, 19 of them have been declared by Trump.
The oldest still active one was made by Carter in 1979, it’s a sanction on Iran.