London: A section of the Turkish military, the second-largest army in NATO after the United States', caught the world off guard on Friday by staging an attempted coup.

The move stunned Turkey observers, who believed President Recep Tayyip Erdogan of the Islamic-rooted Justice and Development Party had brought the secular-minded army to heel.

Acting army chief General Umit Dundar announced Saturday the putsch had been foiled.

The Turkish army, which comprises 510,600 troops, down from around 800,000 in 1985, is considered one of the best trained in the world.

Over the past year it has been focusing most of its energies on fighting separatists from the Kurdistan Workers' Party (PKK) in the south-east and carrying out air strikes against PKK bases across the border in northern Iraq.

Hundreds of Turkish military personnel have been killed in the fighting which restarted after the collapse of a two-and-a-half-year truce in mid-2015.

Turkey last year also joined the US-led coalition that has been pummelling Islamic State jihadists in Syria from the air.

According to 2016 figures from the International Institute for Strategic Studies (IISS), the country has 402,000 soldiers (77,000 professionals and NCOs/325,000 conscripts) in its land force, 48,600 in the navy (14,100/34,500) and 60,000 in the air force.

Added to this are more than 100,000 members of the gendarmerie, or paramilitary police, who fall under the command of the Ministry of the Interior rather than National Defence, according to figures from 2015.

Turkey also has a total of nearly 400,000 reservists in the three services.

The navy has 13 submarines, 18 frigates and six corvettes, while the air force can currently draw on over 200 F-16s, the second-biggest number after the United States.

‘The airforce is well equipped and well trained,’ the IISS report said.

Security intelligence group Jane's says the land army has also come a long way since the early 1990s, developing ‘highly mobile forces with greatly enhanced firepower.’