The military council ordered Parliament dissolved just before the presidential election last month, after a court ruled that the law under which it had been elected was partly unconstitutional. In the same stroke, the military assumed legislative power and severely limited the authority of the presidency, in what many likened to a coup aimed at curbing the power of the Muslim Brotherhood, the Islamist movement that held about half the seats in Parliament.

When Mr. Morsi, the Brotherhood’s candidate, won the presidency, many wondered whether he would directly confront the military council, known as the SCAF, or seek an accommodation, an approach the Brotherhood often seemed to favor. “This could be the early signs of a deal, or the early signs of a battle between the military council and the Brothers,” said Ahmed Ragheb, a human rights lawyer. “Morsi used his powers as president, just like the military used its power as acting president before.”

The announcement on Sunday suggested that Mr. Morsi was willing to stake his credibility on a challenge to the military’s version of power sharing, which left the president’s legislative agenda and even his budget dependent on the generals. The decree “certainly amounts to a confrontation with the judiciary,” said Nathan J. Brown, a political science professor at George Washington University. “It probably amounts to a very bold confrontation with the SCAF as well, though we don’t know what understanding may have been reached there.”

Mr. Morsi’s decree comes with a time limit: the current Parliament is to serve only until a new constitution can be completed, followed by fresh legislative elections within 60 days. Mr. Brown and others suggested that this provision was intended to soften the blow to the military, if only slightly, by acknowledging the court’s demand for a new Parliament.

The wording of the decree left many questions unanswered. It was not clear whether the new election would replace the entire Parliament, or just the members whose seats were most at issue in the court case, amounting to one-third of the total. Analysts also pointed out that any laws passed by the reconvened Parliament could be vulnerable to strong legal challenges.