ATLANTIC OCEAN (May 24, 2021) Underway in the Atlantic Ocean, West of Lisbon, on May 24, 2021. Steadfast Defender 2021 is a defensive exercise based on an Article 5 scenario which is designed to deter aggression and respond to crisis if necessary. Petty Officer Spanish Navy Laura Pons Miles/Released. NATO's Steadfast Defender 2021's Maritime Live Exercise is taking place from 20-30 May, 2021 in the vicinity of Lisbon, Portugal. (NATO photo by Petty Officer Spanish Navy Laura Pons Miles)