Generally, if the Trademark Office determines that the trademarks are not similar, the success rate of the other party’s reexamination will not be very high, but it will also depend on evidence and other relevant materials. The reexamination time will be relatively long, probably about 2 years. As for whether to conduct a defense, it depends on you. Of course, a defense will be better, but not defending will not affect the normal review. It is possible that the other party is just trying to delay your registration and delay the time for you to get the registration certificate.