ISTANBUL (Reuters) - President Tayyip Erdogan's pledge to launch military operations soon to expand safe zones already set up across Turkey's southern borders has raised the stakes in his row with NATO partners over Finland and Sweden joining the alliance.
Analysts said Erdogan's surprise announcement on Monday reflected his belief that the West would not oppose such operations at a time when it needs Ankara's support for the Nordic countries' bid to join NATO.
Turkey accuses Sweden and Finland of harbouring people linked to the outlawed militant Kurdistan Workers Party (PKK). All 30 NATO countries must agree the Nordic states' application to join. The United States said on Tuesday it was confident that Sweden and Finland could overcome Turkey's concerns.
Analysts said Erdogan's announcement was also aimed at bolstering Turkish nationalist support for his two-decade rule as he gears up for difficult elections next year. Cross-border military operations have boosted his poll ratings in the past.
Turkey has conducted three incursions into northern Syria since 2016, seizing hundreds of kilometres of land and pushing some 30 km (20 miles) deep into the country, in operations targeting mainly the U.S.-backed Syrian Kurdish YPG militia.
It has also stepped up military operations against PKK militants in northern Iraq in recent years.
Turkey views both groups as a single terrorist entity. Its NATO allies only view the PKK as a terrorist group, not the YPG.
Asli Aydintasbas, Istanbul-based senior policy fellow at the European Council on Foreign Relations, said Erdogan's move was about testing Turkey's NATO allies.
"President Erdogan's style of meeting international challenges is upping the ante - and it almost always works in causing NATO allies to blink," she said.
"It worked in the eastern Mediterranean and in Syria in the past - why not try again."
Erdogan said operations to combat threats from across the border would start once Turkey's armed forces and intelligence had completed their preparations, with decisions set to be made at a National Security Council meeting on Thursday.
The YPG, or People's Defence Units, are a key element of the Syrian Democratic Forces (SDF), the Kurdish-led coalition which the United States has largely relied on to fight Islamic State militants since 2014.
Commenting on Erdogan's announcement, the SDF accused Turkey of attempting to "destabilise the region" by threatening military action in northern Syria.
The SDF also said it had shot down a Turkish drone on Sunday which it said Ankara has used for surveillance of SDF-held areas ahead of planned shelling.
"In case of any attack, of course we will resist and fight back. The international community now faces an important test: will it effectively rein in Turkey?" said Ciwan Mulla Ibrahim, spokesperson for the SDF-controlled autonomous administration in northeast Syria.
Syria's foreign ministry in Damascus did not immediately respond to requests for comment. There was also no immediate comment from Washington.
Erdogan said the planned military operation would reveal which countries respected Turkey's security concerns and which did not - an issue that cuts to the heart of the current NATO row.
Dareen Khalifa, analyst on Syria at the International Crisis Group, said a Turkish military move against the YPG was always possible despite the relative calm along Turkey's border with YPG-held areas in northern Syria since 2019.
While mediators including the United States have managed to calm tensions in recent years, "the crux of the issue - Turkish-PKK relations - hasn't been addressed", she said.
Erdogan hopes to leverage the issue of Swedish and Finnish membership of NATO into an opportunity to achieve his long-held goal of creating a buffer zone free of Kurdish fighters along Turkey's entire border with Syria, analysts said.
His move comes as opinion polls show support for Erdogan and his ruling AK Party sagging amid deepening economic woes. Turkey holds presidential and parliamentary elections in 2023.
Aydintasbas said Turkey had previously staged cross-border operations ahead of elections. But mounting a large-scale military incursion brings risks too.
As well as the YPG presence, Russia has forces deployed in the area to support Syrian President Bashar al-Assad.
U.S. troops, Turkey-backed insurgents, Iran-backed fighters, jihadists and Syrian government forces also operate across the patchwork of territories in northern Syria.
(Reporting by Daran Butler and Jonathan Spicer in Istanbul, and Maya Gebeily in Beirut; Writing by Daren Butler; Editing by Gareth Jones)