Finland and Sweden are preparing for an enlarged NATO naval exercise in the Baltic Sea on Sunday, amid Turkish concerns over their membership.
NATO's fortnight-long 'Baltops 22' is being hosted this year by Sweden, with the Finnish Navy and Air force also taking part.
Military leaders have suggested it is no coincidence the NATO military drill is larger than in previous years.
US Commander, Vice Admiral Eugene Black, told reporters Saturday: "The exercise this year is probably about 30 per cent bigger than last year.
"45 ships, 76 aircraft, 16 nations - 14 of them NATO allies, and two very close partners" will be involved, he added.
"The aim of the exercise is to develop the interoperability of the United States, Nato and partner countries in joint air and maritime operations and amphibious operations," the Finnish Defence Forces said in a statement on Wednesday.
Around 200 Finish Navy personnel will join the exercise from 5 to 17 June.
Both Sweden and Finland have reversed traditional policies of neutrality by making bids to join the 30-member defensive alliance, following Russia's invasion of Ukraine.
Top US General Mark Milley on Friday met Finnish President Sauli Niinisto to pledge US support for the Nordic duo's NATO membership, with the shallow Baltic Sea now having a pivotal role in the alliance's defensive calculus.
While still pending, Sweden and Finland's membership bids have been blocked by Turkey and criticised by the country's president, Recep Tayyip Erdoğan.
"I speak very clearly about Sweden and Finland in NATO," said Erdoğan at the opening of Turkey's ruling AK Party's 30th Consultation and Evaluation Meeting in the Kizilcahamam district in Ankara. "The whole world should know this: NATO is not an organisation that will provide security against terrorism."
Turkey is angered at what it sees as Sweden and Finland's willingness to host Kurds affiliated with the Kurdistan Worker's Party, which has waged a decades-long insurgency against the Turkish state.
Sweden and Finland blocked arms exports to Turkey after it launched a military incursion in 2019 into northern Syria.
Erdogan added: "Right now, terrorist organisations are going freely around in Sweden and Finland, carrying the posters of the terrorist organisation head, doing this under the security of the Swedish and Finnish police, doing these under the security of the German, French, and Dutch police, while all these campaigns are being carried out against Turkiye."
Both Sweden and Finland have repeatedly denied that they are providing financial assistance or military support to Kurdish groups or entities in Syria.
All member states must agree before a new country can be admitted into NATO.
Meanwhile, around 1,800 troops from eight NATO countries are taking part in a drill organised in southeastern Romania.
NATO has also been beefing up its presence here since Russia launched its military assault on Ukraine in February.