Russia on Wednesday said two of its warships were heading back to join its forces in the Mediterranean amid an upsurge in tensions with Washington over Syria. 

President Vladimir Putin on Monday called for a boost of Russia's defenses to keep the nation "strong" as he opened the new parliament session amid a fresh upsurge in tensions with the United States.

Putin addressed the State Duma after a crushing victory for ruling party United Russia at elections last month that could help smooth the way for him to claim a fourth term as president in a vote set for 2018.

An air strike was responsible for the attack on an aid convoy in Syria that killed 18 people last month, a U.N. expert said Wednesday.

"With our analysis we determined it was an air strike," said Lars Bromley, a researcher at the United Nations body UNOSAT, which collects and analyses satellite images. 

A delegation from the world's only permanent war crimes court is visiting Israel and the Palestinian territories this week to "promote better understanding" about its work, the chief prosecutor said Wednesday.

Three children were among at least 19 civilians killed in an air strike on a village held by the Islamic State group in northern Syria on Wednesday, a monitor said.

Israeli tank fire struck a Hamas post in the Gaza Strip on Wednesday after a rocket launched from the Palestinian enclave hit a nearby Israeli city, with no casualties reported on either side.

Iraq and Turkey on Wednesday were summoning their respective ambassadors in an increasingly acrimonious dispute between the two neighbors ahead of a planned operation to retake the Iraqi city of Mosul from jihadists.

Ankara called in the Iraqi ambassador while Baghdad said it had decided to summon the Turkish envoy following bitter verbal exchanges, the two foreign ministries said.

The United Arab Emirates said on Wednesday that there were injuries among civilian crewmen of a vessel hit by Yemeni rebels in the strategic Bab al-Mandab waterway last week.

The foreign ministry did not say how many were wounded in the Friday night attack but said they were receiving treatment in the UAE.

One Turkish soldier was killed during clashes with extremist fighters in Syria as Ankara's ambitious operation in the country's north approaches its second month, state media reported on Wednesday.

Three other soldiers were slightly injured in the confrontation with Islamic State group militants in Ziyara, east of Al-Rai town, the official Anadolu news agency said, quoting the Turkish armed forces.

Twenty-eight Europe-bound migrants were found dead on a day of frantic rescues off Libya on Tuesday, including at least 22 in an overloaded wooden boat, an AFP photographer and the Italian coastguard said.