Lebanon’s Prime Minister Saad al-Hariri (C), gets out of a vehicle outside the Parliament building before his new government won a vote of confidence in parliament in downtown Beirut, Lebanon December 28, 2016.

Lebanon’s Prime Minister called Hezbollah’s arms illegitimate on Tuesday after its President said the group’s military wing was vital to its security, spelling out the country’s political divisions more clearly than at any time since they took office.

A staunch Hezbollah ally, Michel Aoun became president in October in a power-sharing deal that saw Saad al-Hariri, Lebanon’s leading Sunni Muslim politician, appointed premier in a unity cabinet including nearly all Lebanon’s main parties.

The powerful arsenal wielded by Sh’ite Iranian-backed Hezbollah outside the state’s control has long been a subject of controversy, with several major political parties calling for the group’s disarmament, while others support it.

Hezbollah has become deeply embroiled in the war in Syria, where its forces are fighting in support of President Bashar al-Assad.

The Lebanese state has adopted a policy of official neutrality towards the conflict. Hariri said on Tuesday that, despite sharp disputes over Hezbollah’s arms, “the consensus on the role of the army, legitimate forces and the state” protected Lebanon.

“We will not compromise on the fundamentals … our view of the Assad regime and its crimes, our stance towards the illegitimate arms and … Hezbollah’s involvement in Syria,” he said at a ceremony in central Beirut marking the 12th anniversary of his father’s assassination.

Aoun said in an interview with the Egyptian channel CBC last week that Hezbollah’s arms “do not contradict the state… and are an essential part of defending Lebanon.

“As long as the Lebanese army lacks sufficient power to face Israel, we feel the need for (Hezbollah’s) arsenal because it complements the army’s role,” he said.

Hezbollah, whose fighters played a major role in Israel’s withdrawal from southern Lebanon in 2000, backed Aoun’s election. In addition to its powerful military wing, the group wields strong political influence.

Rafik al-Hariri was killed in a 2005 Beirut waterfront bombing that also killed 21 others, shaking the country and pushing his son Saad into politics.

Hariri and his allies initially accused Syria of killing Rafik. A UN-backed tribunal later charged five Hezbollah members over the killing. Hezbollah denies any role.

Their trial in absentia at the Hague began in January 2014, and Hezbollah and Damascus have both denied any involvement in the killing.