CAIRO – Egypt’s Islamist-dominated parliament opened a new front in the country’s leadership showdowns Tuesday by meeting in defiance of orders that disbanded the chamber and brought President Mohammed Morsi in conflict with both the powerful military and the highest court.

The session was brief – lasting just five minutes – and suggested that lawmakers sought more of a symbolic stance rather than a full-scale backlash against rulings that invalidated the chamber over apparent irregularities in elections.

But it further nudged Egypt deeper into a potential power struggle between Morsi and military chiefs, who have vowed to uphold a ruling by the Supreme Constitutional Court that led to parliament being dissolved last month.

Morsi countered with his own decree ordering the 508-seat chamber to reconvene. The constitutional court fired back Tuesday, ruling that Morsi’s decision had no legal grounding.

For the moment, all sides appear to be moving with some caution in acknowledgment of Egypt’s volatile backdrop: The military with the power to clamp down on dissent but without widespread support on the streets where Morsi’s Muslim Brotherhood is strong.

Security forces made no attempt to block lawmakers as they arrived at the parliament building in central Cairo. Later, thousands joined a pro-Morsi rally in Cairo’s Tahrir Square as riot police kept their distance. News of the court’s ruling against Morsi was greeted with chants of “batel,” or illegitimate, by the crowds.

The crisis atmosphere has grown steadily since Morsi issued an order Sunday to reconvene the legislature. His executive order said it was revoking the military’s June 15 order to disband the chamber based on the previous ruling by the Supreme Constitutional Court.

The court said a third of the chamber’s members were elected illegally by allowing candidates from political parties to contest seats set aside for independent candidates.

Morsi’s presidential decree also called for new parliamentary elections after a new constitution is adopted, which is not expected before the end of the year. In effect, it puts the current parliament in a sort of caretaker status.

The dispute over the fate of parliament has divided the nation just as Egyptians hoped for a semblance of stability after the tumult since the Arab Spring ouster of Mubarak. Egypt has seen a dramatic surge in crime, deadly street protests, a faltering economy and seemingly non-stop strikes, sit-ins and demonstrations.

The latest crisis drew a warning from U.S. Secretary of State Hillary Rodham Clinton, who is scheduled to visit Egypt this weekend. She urged Morsi and the military to settle their differences or risk seeing their nation’s democratic transition derailed.