Spain's leftist government has closed Spanish airspace to U.S. planes carrying out missions against Iran in addition to denying Washington use of its bases, the defense minister said on Monday.

"The bases are not authorized, and of course neither is the use of Spanish airspace for actions related to the war in Iran," Margarita Robles told journalists, confirming a report by El Pais daily.

Sirens sounded at dawn near Israel's main nuclear research center, a part of the country that has been targeted repeatedly in recent days. Israel's military also said it had taken out two drones launched from Yemen, where the Iranian-backed Houthi rebels entered the war on Saturday with their first missile attack.

Later, a fire broke out at an oil refinery in the northern city of Haifa, one of only two in Israel, either from a missile strike or from debris falling from an interception. The blaze was quickly extinguished.

Israel's parliament on Monday passed its annual budget in a marathon overnight session, ensuring that Prime Minister Benjamin Netanyahu's government can complete its term until the fall.

Israel needed to pass a budget before April 1 in order to avoid triggering early elections. Netanyahu still reserves the right to call early elections before then if he wants.

U.S. President Donald Trump openly mused about seizing Iran's Kharg Island oil terminal in the Persian Gulf and the United States and Israel kept up their attacks Monday on the Islamic Republic, even as there were signs of progress in nascent ceasefire talks. Tehran, meanwhile, struck a key water and electrical plant in hard-hit Kuwait, part of its campaign targeting the Gulf Arab states.

As a diplomatic effort being facilitated by Pakistan toward ending the war moved ahead, Trump said Iran had agreed to allow 20 oil tankers through the Strait of Hormuz starting Monday as "a sign of respect." At the same time, with 2,500 U.S. Marines now in the region and a similar sized contingent on its way, he raised the idea of taking Iran's Kharg Island.

Syria's military said a large-scale drone attack targeted its bases near the border with Iraq on Monday, the latest such incident since the outbreak of the Middle East war.

In a statement, the army reported "a large-scale attack by a number of drones targeting several army bases near the Iraqi border at dawn today", adding that most of the drones were intercepted.

Iran's parliament speaker, Mohammad Bagher Ghalibaf, said Sunday that the United States was plotting a ground attack despite publicly engaging in diplomatic efforts aimed at ending the war.

"The enemy publicly sends messages of negotiation and dialogue while secretly planning a ground attack," Ghalibaf said in a statement carried by the official IRNA news agency.

The Revolutionary Guard’s warning on Sunday said it would consider Israeli universities and branches of American universities in the region “legitimate targets,” state media reported.

Top diplomats from key regional powers were gathering in Pakistan on Sunday to discuss how to end the fighting in the Middle East, but there were few signs of progress as Israel and the U.S. kept up strikes on Iran, and Tehran responded by firing missiles and drones across the region.

Pakistan said foreign ministers from Saudi Arabia, Turkey and Egypt were participating in the talks in Islamabad. Pakistani Prime Minister Shehbaz Sharif said he and Iranian President Masoud Pezeshkian held "extensive discussions" on regional hostilities.

Iran has agreed to allow humanitarian aid and agricultural shipments through the Strait of Hormuz following a request from the United Nations.

Pakistan said Saturday Saudi Arabia, Turkey and Egypt will send their top diplomats to Islamabad for talks aimed at ending the Iran war.