Finnish president says he was 'astonished' that Turkey's President Erdogan suggested he might block Finland's NATO application

On Sunday, Sauli Niinist said that he was astonished by the suggestion that Turkey might block Finland from joining NATO after he was told he would be fine with it.

I had a telephone discussion with the president. Niinist told Dana Bash on CNN that they will estimate positively our aim to apply for membership. And now it has changed.

A historic reversal of the Nordic nation's decades of neutrality was signaled on Sunday. Sweden could soon join its neighbor in applying for NATO membership.

Turkey did not hold positive views about either Sweden or Finland joining the North Atlantic Treaty Organization, according to the president. NATO's other 29 members must unanimously accept any new applications from Turkey, which is of paramount importance.

NATO Secretary-General Jens Stoltenberg and Secretary of State Antony Blinken tried to downplay the comments. Turkey's concerns could be worked out, according to two people on Sunday.

I'm confident that we will be able to address the concerns that Turkey has expressed in a way that doesn't delay the membership or the accession process.

Niinist said he was not worried about the views of the man.

The accusation is likely a reference to Sweden's support for the Kurdish-led Syrian Democratic Forces. Tensions between the two NATO members have arisen because of the US' support of the SDF.

The main partner in the fight against Isis has been the SDF.