Genocide and war-crimes charges have long shadowed Sudan’s president, sometimes forcing him to scrap or alter travel abroad to avoid the risk of arrest and extradition to the International Criminal Court. Still, Sudan said Monday, he had accepted an invitation to visit Russia next month.

The invitation to the president, Omar Hassan al-Bashir, from President Vladimir V. Putin of Russia, presents a new test of Mr. Bashir’s defiance of the international court at The Hague, which issued arrest warrants for him years ago over the genocide in Sudan’s Darfur region.

Mr. Bashir’s refusal to heed the warrants has come to symbolize a broader impunity shown toward the court, the international judicial authority that was created to deal with egregious crimes in which victims have no other recourse.

The invitation to Mr. Bashir also may partly reflect a concerted effort by Mr. Putin to reassert Russian influence at a time of retreat for the United States in parts of the Middle East and sub-Saharan Africa.