Pakistan, Turkey and Saudi Arabia have reached a mutual defense agreement as Iran-backed Houthi rebels have intensified attacks against targets associated with Saudi Arabia.

Saudi Arabia, Pakistan—a nuclear-armed country—and Turkey, which has NATO’s second-largest military and a rapidly expanding defense sector, signed the agreement on Friday.

Under the pact, an armed attack against any one of the three nations will be treated as an attack against all three. The agreement was concluded during a meeting in Saudi Arabia attended by Saudi Crown Prince Mohammed bin Salman, Turkish President Recep Tayyip Erdogan and Pakistani Prime Minister Shehbaz Sharif, according to Pakistan’s foreign ministry.

The ministry said the agreement aims to enhance joint deterrence and strengthen the three countries’ ability to respond collectively to acts of aggression.

The agreement comes as Saudi Arabia seeks to broaden its defense relationships. The kingdom has faced attacks on important infrastructure and oil facilities amid the ongoing conflict involving Iran.

U.S. Could Lift Iran Port Blockade if Strait of Hormuz Agreement Is Reached

A U.S. official said Friday that President Donald Trump would end the American blockade of Iranian ports if Iran agrees to an acceptable arrangement for reopening the Strait of Hormuz and complies with the terms.

According to the official, regional mediators have informed the U.S. administration that Iran and Oman could reach an agreement concerning the strategically important waterway within the next few days. Washington is expected to review the outcome of the Iran-Oman negotiations before deciding how to respond.

The official, who spoke anonymously while discussing internal government deliberations, also stressed that the United States would reject any arrangement allowing Iran to impose tolls, service charges or other restrictions on ships passing through the strait.