Donald Trump’s decision to recognize Jerusalem as Israel’s capital is a “declaration of war,” the leader of Hamas said Thursday, while calling for another uprising against the Jewish state.

The tirade from the head of the Palestinian Islamist group came as clashes broke out at protests in the West Bank and Gaza.

Ismail Haniyeh said Trump’s Wednesday speech reversing seven decades of U.S. policy regarding the holy city had “killed the peace process.”

“The US decision is an aggression, a declaration of war on us,” he said. “We should work on launching an intifada in the face of the Zionist enemy.”

He said Hamas members had been instructed to prepare for “orders that may be given to confront this strategic danger that threatens Jerusalem and threatens Palestine.”

His comments came as violence broke out at protests across the Palestinian territories Thursday, with marchers burning Israeli and American flags and chanting anti-Trump slogans.

In Bethlehem, Israeli forces used tear gas and water cannon to drive back protesters who were burning tires and throwing stones, while near Ramallah, stun grenades and tear gas were deployed.

The rallies followed protests Wednesday that spread to Iraq, Jordan, Tunisia, and Turkey, where more than 1,000 people gathered outside the U.S. consulate in Istanbul to chant, “Down with America.” The unrest is expected to grow, with Hamas calling on Muslims worldwide to hold a “day of rage” Friday.

Israel’s defense force is reinforcing troops in the West Bank and has placed others on standby in preparation.

The status of Jerusalem is a core issue in the Israeli-Palestinian conflict, with both sides claiming the city as their capital. The final status of the city was set to be determined in the latter stages of negotiations for a two-state solution.

Critics of Trump’s decision, which has been almost universally condemned by the international community, say it will damage the prospects for peace, and jeopardize U.S. national security.

Harakat Hezbollah al-Nujaba, the powerful Iranian-backed militia in Iraq, said the decision could be a “legitimate reason” to attack U.S. forces.

And Ayatollah Ali Sistani, the influential Shia cleric in Iraq, said Thursday the move had “hurt the feelings of hundreds of millions of Arabs and Muslims.”

Andreas Krieg, a Middle East expert at King’s College London, told VICE News that in pandering to his domestic base of conservatives and the religious right, Trump was meddling with what was seen as a red line by much of the Muslim world.

“For the vast majority of the Muslim world, the Dome of the Rock remains the third holiest site (in Islam), which must not be given up,” he said. “This is why previous presidents have not given in to Judeo-Christian neoconservative pressure to make Jerusalem the ‘eternal capital of the Jewish homeland’.”

He said the decision would also put domestic pressure on U.S. allies in the region, such as Saudi Arabia, Jordan and the United Arab Emirates, strain their relationships with Washington and undermine U.S. policy in the volatile region.