Don't make grave mistake

• Russian warplanes resume bombing Idlib province
• UN again warns of humanitarian catastrophe
• Israeli planes target military positions in Syria

US President Donald Trump on Monday warned Syria against launching an attack on the country's last rebel stronghold with the help of Russia and Iran, saying the offensive could trigger a "human tragedy."

The warning came as Iran's foreign minister Mohammad Javed Zarif met with Syrian leader Bashar al-Assad in a surprise visit to Damascus ahead of the looming offensive.

Syrian forces are amassing around the northwestern province of Idlib, in preparation for the assault.

"President Bashar al-Assad of Syria must not recklessly attack Idlib Province. The Russians and Iranians would be making a grave humanitarian mistake to take part in this potential human tragedy," Trump tweeted.

"Hundreds of thousands of people could be killed. Don't let that happen!"

The United Nations and aid groups have warned that a full assault on Idlib could spark a humanitarian catastrophe on a scale not yet seen in Syria's seven-year-old conflict.

But Russia and Iran have insisted that extremist groups in Idlib must be defeated and are expected to back regime forces in any assault, reported AFP.

The Kremlin dismissed Trump's warning, saying that the area was a "nest of terrorism", reported Reuters.

"Just to speak out with some warnings, without taking into account the very dangerous, negative potential for the whole situation in Syria, is probably not a full, comprehensive approach," Kremlin spokesman Dmitry Peskov said.

Meanwhile, Russian warplanes yesterday battered Idlib for the first time in three weeks, a war monitor said. Yesterday's bombardment hit several areas held by the jihadist-led Hayat Tahrir al-Sham alliance, among them the large town of Jisr al-Shughur, but also areas held by rival Turkish-backed rebels, including the town of Ariha.

In a sign of the looming complex assault, Israeli planes yesterday targeted military positions in Syria, but Syrian air defences confronted and downed some of the rockets, state news agency SANA.

Citing a military source SANA said that Israeli aircraft had targeted "our military positions in the provinces of Tartous and Hama".

The Syrian Observatory for Human Rights war monitor said several explosions had been heard in the areas around Masyaf and Wadi al-Uyoun near Hama city, areas where there are Iranian military facilities.