President Donald Trump on Sunday night said he has "no problem" with a Russian oil tanker off the coast of Cuba delivering relief to the island, which has been brought to its knees by a U.S. oil blockade.

"We have a tanker out there. We don't mind having somebody get a boatload because they need … they have to survive," Trump told reporters as he flew back to Washington.

Spain has closed its airspace to U.S. planes involved in the Iran war, Defense Minister Margarita Robles said Monday, marking another step in the country's opposition to the U.S. and Israel's conflict in the Middle East.

Spain had already said the U.S. could not use jointly operated military bases in the Iran conflict, which Spanish Prime Minister Pedro Sánchez has described as illegal, reckless and unjust.

Iran on Monday defied Lebanon's expulsion order for its ambassador by saying he would stay, further increasing tensions in a country in the crosshairs of the latest fighting between the Iranian-backed Hezbollah and Israel.

Lebanon had declared Ambassador Mohammad Reza Shibani "persona non grata" in an effort to weaken Iran's diplomatic presence and have a charge d'affairs at its embassy instead. But the deadline to leave the country was Sunday.

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.

As Christians packed churches across Lebanon this Palm Sunday to commemorate their belief in Jesus' triumphal entry into Jerusalem, the renewed war between Israel and Iran-backed Hezbollah weighed on parishioners.

Still, it was standing-room-only at a Maronite Catholic church near Dahieh, in Beirut's southern suburbs, a once-densely populated Shiite district — now emptied by sweeping Israeli evacuation orders and constant airstrikes. In the coastal city of Tyre in southern Lebanon, which has been almost cut off from the rest of the country by Israel bombing surrounding bridges, the peal of church bells and velvety choral music filled the air.

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.

The Lebanese health ministry said a strike Saturday evening on Hanniyeh town in Tyre province killed seven people, six Syrians, including a child, and one Lebanese person, and wounded nine others.

Mourners gathered on Sunday in Choueifat, south of Beirut, for the funerals of three journalists killed by an Israeli airstrike.

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.