A Syrian refugee in the US was arrested Wednesday on suspicion of planning an attack against a Pennsylvania church in the name of the Islamic State group, the Justice Department said.

A U.S. official said Wednesday that Saudi Arabia should do more to ensure accountability over the death of dissident writer Jamal Khashoggi but stopped short of blaming the crown prince after a U.N. probe linked him to the killing.

Regime attacks killed 16 civilians and nine combatants in Syria's jihadist-run northwest on Wednesday, a war monitor said, the latest violence to rattle a region housing three million people.

With tensions rising between Israel's ally the U.S. and its archfoe Iran, Israeli Prime Minister Benjamin Netanyahu warned Israel's enemies not to test it Wednesday, his office said.

Prime Minister Benjamin Netanyahu has said that Israelis will take part in a conference in Bahrain next week that is part of the United States' Middle East peace plan.

A Japanese tanker attacked in the Gulf of Oman last week was damaged by a limpet mine resembling Iranian mines, the US military in the Middle East said on Wednesday.

"The limpet mine that was used in the attack is distinguishable and it is also strikingly bearing a resemblance to Iranian mines that have already been publicly displayed in Iranian military parades," Commander Sean Kido of US Naval Forces Central Command said. 

US assets in Iraq have been targeted at least five times in as many days, officials said Wednesday, amid a tense standoff between Baghdad's key allies, Washingon and Tehran.

A Saudi-led coalition fighting in Yemen intercepted a Huthi rebel drone targeting the kingdom, a spokesman said Wednesday, calling it another violation of an already fragile ceasefire in a key Red Sea province.

The unmanned drone was shot down in Yemeni airspace after the Iran-aligned rebels launched it from Hodeida province, coalition spokesman Turki al-Maliki said in comments carried by the official Saudi Press Agency.

There is "credible evidence" linking Saudi Arabia's Crown Prince to the killing of Saudi journalist Jamal Khashoggi last October, a report by an independent United Nations rights expert said Wednesday.

Israel is holding its largest military drill in years, with thousands of troops from the army, navy and air force simulating a future war with Lebanese Hizbullah militants.