Syrian insurgents led by the Hayat Tahrir al-Sham group, which evolved from al-Qaeda's former branch in Syria, launched a two-pronged attack on Aleppo and moved into the countryside around Idlib and neighbouring Hama province.

Iraqi Major General Yahya Rasool, the spokesperson for the Commander-in-Chief of the Armed Forces, announced on Monday the deployment of "armoured units" from the Iraqi army towards the country's western borders in light of the attacks by armed factions in neighbouring Syria.

Iraq has placed all its military sectors on a state of emergency following the developments in Syria, accompanied by diplomatic efforts aimed at "keeping the country away from what is happening in Syria."

The Iraqi Ministry of Interior said that "the Iraqi-Syrian border is the most secure," affirming that "it cannot be breached."

"The situation cannot be compared to 2014," Iraqi Interior Ministry Spokesperson General Muqdad Miri said, referring to the fall of Iraq's city of Mosul into the hands of ISIS militants.

On Saturday, Iraqi Prime Minister Mohammed Shia al-Sudani told Syrian President Bashar al-Assad that his country's security was crucial to the region's stability.

"Sudani emphasized that Syria's security and stability are closely linked to Iraq's national security and play a crucial role in regional security and efforts to establish stability in the Middle East," his office said.

Iran shadow
 

As Iran's shadow never fades from the political scene in Iraq, Syrian and Iraqi sources told Reuters on Monday that hundreds of fighters from Iran-backed Iraqi militias crossed into Syria overnight to help the government fight insurgents who seized Aleppo last week.

According to a Reuters report, at least 300 fighters, primarily from the Badr and al-Nujaba groups, crossed late on Sunday using a dirt road to avoid the official border crossing, two Iraqi security sources said.

Harakat al-Nujaba is one of the largest factions within the Popular Mobilization Forces (PMF) in Iraq.

The faction, which has participated in battles against the Islamic State in the country, maintains close ties with Lebanon's Hezbollah and the Iranian Revolutionary Guard Corps (IRGC).

It also fought alongside the Syrian army and contributed to the capture of the eastern parts of Aleppo city in northern Syria in late 2016.

The Badr Organization is an Iraqi Shia armed group which established in 1982 under Iranian influence during Ayatollah Khomeini's era.

The group was considered the military wing of the "Islamic Supreme Council" in Iraq. 

It participated alongside Iran in its war against Iraq, contributed to the overthrow of Saddam Hussein, was accused of targeting Iraqi officials, and fought at one point alongside the Syrian army under President Bashar Al-Assad.

Additionally, the Syrian Observatory for Human Rights, a UK-based opposition war monitor, said some 200 Iraqi militiamen on pickups crossed into Syria overnight through the strategic Bou Kamal crossing. They were expected to deploy in Aleppo to support the Syrian army’s pushback against the insurgents, the monitor said.

However, the Iraqi Ministry of Interior denied any movement of armed factions crossing the Syrian border, describing the circulated reports as "fabricated."

During a press conference, the ministry's spokesperson refuted claims reported by Reuters that fighters belonging to "Iran-aligned" armed had crossed from Iraq into Syria.

The spokesperson stressed that this information is "fabricated talk" circulating on Facebook, emphasizing that no movements have been recorded on the border.

On Monday, Iranian President Masoud Pezeshkian confirmed in a phone call to President Al-Assad on Monday that Tehran was ready to provide all the support needed to repress the insurgency.

Iran, along with its Lebanese ally Hezbollah, has backed President Al-Assad in his decade-old war against various insurgencies.