OUAGADOUGOU—Burkina Faso’s army said on Monday it had ousted President Roch Kabore, suspended the constitution, dissolved the government and the national assembly, and closed the country’s borders. The announcement cited the deterioration of the security situation and what the army described as Kabore’s inability to unite the West African nation and effectively respond to challenges, which include an Islamist insurgency. Signed by Lieutenant Colonel Paul-Henri Sandaogo Damiba and read by another officer on state television, the announcement said the takeover had been carried out without violence and that those detained were at a secure location. The statement was made in the name of a previously unheard-of entity, the Patriotic Movement for Safeguard and Restoration, or MPSR, its French-language acronym. “MPSR, which includes all sections of the army, has decided to end President Kabore’s post today,” it said. Kabore’s whereabouts were unknown on Monday, with conflicting accounts of his situation. Army …