President Vladimir V. Putin of Russia signed a decree on Wednesday simplifying the citizenship process for people in separatist-held regions of Ukraine, issuing a challenge to Ukraine’s president-elect that threatens to intensify the five-year war in the country’s east.

The decree, published on the Kremlin’s website, said that some residents in the regions of Donetsk and Luhansk, eastern parts of Ukraine controlled by Russia-backed rebels, could have their applications for Russian citizenship considered for acceptance within three months.

The order to simplify the citizenship process was made for the “humanitarian goals” of defending the “rights and freedoms of a person and citizen, outlined by the universally accepted principles and norms of international law,” its text said.

Yet the decree was immediately perceived as a challenge in Washington and Kiev, the Ukrainian capital, where the outgoing president has tried to rally the country on a platform of war and nationalism and the incoming president will take office with no political experience.