(Reuters) -Exchange operator Cboe Global Markets on Friday declared a regulatory halt in trading on the VanEck Russia ETF, which has tumbled since Russia’s invasion of Ukraine last week. Cboe also said it was halting trading of the much smaller VanEch Russia Small-Cap ETF. “Cboe BZX Exchange has declared a Regulatory Halt in RSX and RSXJ that is effective for all U.S. equities markets. As a result of this trading halt in RSX and pursuant to its rules, trading in the options in RSX on Cboe’s options exchanges has been halted,” a Cboe spokesperson said in an email. Following Russia’s invasion of…