No one wants to conquer there, we are not in genghis khan era dude.If you do not think conquer Tajikistan you have nothing to worry about.
Just after Tajikistan join the Eurasian Union, it will report to supranational regulators. You will have to deal not alone with Tajikistan, and with the Eurasian Union.
BTW, I hope you guys treat Uzbeks and Tajiks fairly and do not ignore them for the sake of Uzbeks
for what reason Iran should harm Tajikstan?I support Russia.And iran will not harm a hair of tajikistan as long it is under russian protection .
FYI, Iran has always helped them, specially when their neighbor , Uzbeks, try to put pressure on them by closing railroads.