Iraq's air force has struck Islamic State targets inside Syria for the first time as Iraqi troops on the ground pushed into western Mosul.
Iraq's Prime Minister, Haider al-Abadi, announced the air strikes, saying the air force hit the towns of Boukamal and Husseibah across the border. He said they came in response to recent bombings in Baghdad claimed by IS and linked to the militants' operations in Syria.
Meanwhile, Iraqi forces pushed into the first neighbourhood of western Mosul and took full control of Mosul's international airport and a sprawling military base on the south-western edge of the city, according to Iraqi officials.
The city is the last major urban stronghold held by the Sunni militant group in Iraq.
The territorial gains mark the first key moves in the battle, now in its sixth day, to rout IS militants from the western half of Mosul, Iraq's second-largest city.
The push into Mamun neighbourhood was followed by intense clashes with IS militants, according to an Iraqi special forces officer on the ground.
An Associated Press team near the front line saw at least four wounded special forces members and the bodies of three soldiers, suggesting more intense fighting than the previous day.
Earlier on Friday, the spokesman of the Joint Military Operation Command, Brigadier General Yahya Rasool, said Iraqi forces had also retaken the military base adjacent to the airport.
An Iraqi air force commander said the air strikes against IS Syria were carried out with F-16 warplanes at dawn and "were successful".
The commander said they were conducted at the order of the prime minister.
The advances come a day after special forces joined the fight for western Mosul.
Both the Ghazlani military base and the airport will be key to the next steps in the daunting battle and will serve as a base of operations as Iraqi forces launch subsequent pushes into western Mosul, which is divided by the Tigris River into two halves.
Iraqi authorities declared the city's eastern half "fully liberated" from the Sunni militants in January, three months after launching the operation to take back Mosul.
On Thursday, Iraqi special forces joined federal police and rapid response units in the push while the Popular Mobilisation Forces - an umbrella group of government-sanctioned Shiite militias - secured the main roads west of Mosul, largely cutting the city off from IS-held territory in Syria.
The United Nations has estimated that about 750,000 civilians are trapped in western Mosul. The initial numbers of displaced from western Mosul have been low, but Iraqi forces are yet to punch into the city's dense urban neighbourhoods.
The battle for western Mosul is expected to be the most trying yet. The western half of the city is denser with older neighbourhoods and narrower streets that will likely complicate the already difficult urban combat ahead.