Worries are growing about the whereabouts of a freelance Japanese journalist, last heard from one month ago in war-torn Syria, where reporting assignments have become among the most precarious in the world.

It is not known why Jumpei Yasuda, who has been reporting on the Middle East since 2002, has not been in contact. He may not have access to communications or if he has been taken captive.

Three Spanish freelance journalists have gone missing in Syria where they were reporting from the northwestern Aleppo region, the head of a Spanish press federation said on Tuesday.

Jose Manuel Lopez, Antonio Pampliega and Angel Sastre entered Syria via southern Turkey on July 10 "and there has been no news of them since July 12", said Elsa Gonzalez, president of the Federation of Press Associations of Spain.

The U.S. military flatly denied Tuesday a claim from a Kurdish militia source that it  coordinates air strikes against the IS group in Syria with Bashar Assad's government forces.

Both Syrian and U.S.-led coalition planes have been seen in recent days over Hasakeh in northern Syria, where the so-called Islamic State is battling local Kurdish fighters.

Turkey said on Tuesday it had identified a suspect over a devastating suicide bombing on the border with Syria blamed on Islamic State jihadists, as the government rushed to bolster security on the porous frontier.

Thirty-two people were killed and more than 100 wounded on Monday when a bomb ripped through a crowd of young socialist activists in a mainly Kurdish region preparing to take aid over the border into Syria.

A deadly suicide bombing in southern Turkey appears to be part of the Islamic State group's war against the Kurds, and shows the country's growing vulnerability to the conflict in neighboring Syria, analysts say.

The attack on Monday on a gathering of pro-Kurdish activists in Suruc along the Turkish-Syrian border, which killed at least 32 people, bore the hallmarks of the Sunni extremist organization.

Syrian rebels, including al-Qaida-affiliated fighters, have fired hundreds of rockets and mortar shells on two besieged Shiite-majority villages in the northwestern province of Idlib, a monitor said Tuesday.

At least seven people were reported killed in the shelling by the Army of Conquest alliance on the regime-held villages of Fuaa and Kafraya on Monday and Tuesday, the Syrian Observatory for Human Rights said.

On a hilltop lookout near Israel's border with Lebanon, U.S. Defense Secretary Ash Carter offered personal assurances Monday that the U.S. will help Israel counter Iranian support for Hizbullah. He called it one example of how the U.S. can support the Jewish state in the aftermath of the Iran nuclear deal.

Carter visited Hussein Lookout, with a sweeping view of the border as well as the Golan Heights, in an effort to emphasize U.S. concern about a range of threats that face Israel. These include tens of thousands of short-, medium- and longer-range Hizbullah rockets and missiles in southern Lebanon that could hit Israeli villages and cities.

Uruguay will take in a new group of Syrian refugees by the end of the year, officials said Monday, adding that the country was committed to helping alleviate a humanitarian crisis.

A total of 117 family members are being relocated to Uruguay from refugee camps in Lebanon.

Almost 70 fighters have been killed in the two-week-old battle between pro-government forces and Islamist rebels for control of Zabadani on Syria's border with Lebanon, a monitoring group said Monday.

The Syrian Observatory for Human Rights said 46 rebels and 21 members of Hizbullah fighting on the government side have died since pro-regime forces entered the town of Zabadani on July 4.

A suspected Islamic State suicide bomber killed at least 31 people Monday in an attack on a Turkish cultural center where activists had gathered to prepare for an aid mission in the nearby Syrian town of Kobane.

The blast ripped through the center in Suruc -- a town just across the border from Kobane, which was itself later hit by a suicide car bombing -- blowing out the windows and starting a fire, witnesses said.