President Erdogan is unhappy with the Nordic nations refusing to extradite Kurdish militants.
Sweden and Finland have expressed their interest in joining Nato after the war in Ukraine.
But, without the support of all Nato members, they cannot join, leading to tensions between the countries involved in the organisation. Here’s everything you need to know...
What is Nato?
Nato was established after the end of World War Two to provide collective security against the then Soviet Union.
Although the Cold War may be over, the purpose of Nato remains the same and it still offers collective security to all states that are members.
This means that if a member state is threatened or invaded, Nato will offer that country defence.
Nato is now made up of 30 countries and it has intervened in conflicts including Libya and the Kosovo War.
Russia is not a member of Nato and is staunchly opposed to the organisation.
How can a country join Nato?
If a country wants to join Nato they must be able to meet certain criteria.
Requirements include having a functioning democratic political system, a commitment to civil-military relationships and a stable market economy.
Before a new country can join Nato, it must gain approval from all 30 member states.
Why do Finland and Sweden want to join Nato?
Finland and Sweden both want to join Nato due to Russia’s invasion of Ukraine.
The countries became formal partners of Nato in 1994, but now want to become fully fledged members.
Finland’s close proximity to Russia has caused them to threaten “retaliatory steps” if the nation does indeed join the organisation.
Russian President Vladimir Putin stressed that any expansion of military infrastructure in either Sweden or Finland would trigger a response from the Kremlin.
Why is Turkey blocking Finland and Sweden from joining Nato?
Finland and Sweden cannot join Nato if any members object and so far, Turkey is doing just that.
President Erdogan is refusing to accept any countries that apply sanctions on Turkey.
Both Sweden and Finland have angered Turkey in the past by rejecting calls to extradite Kurish militants who Turkey see as terrorists.
In 2019, both countries also suspended arms sales to Turkey after their military went to Syria.
Speaking in parliament in Helsinki on Monday, Finnish Foreign Minister Pekka Haavisto said he was not interested in "bargaining" with Turkey’s president.
Can a country be kicked out of Nato?
There have been calls to kick Turkey out of Nato in both 2016 and 2019, however removing a member state isn’t straightforward.
Under the North Atlantic Treaty which established Nato, there are no provisions for suspending the rights of any member state, let alone expell them.
Nato instead takes on a diplomatic approach, speaking with member states instead.
Jorge Benitez of the Atlantic Council think tank in Washington, explained that Nato “wait out the misbehaving national leaders until a government consistent with alliance values eventually returns to power”.
One way that a member state can be suspended is through a “Material Breach” under a separate treaty called the Vienna Convention.
To qualify for suspension a state would have to:
- Reject the treaty not sanctioned by the present Convention
- Or violate a provision essential to the accomplishment of the object or purpose of the treaty
So far there has been no indication that Nato is considering suspending Turkey.