The Hungarian parliament approved Sweden's accession to the North Atlantic Treaty Organization on the 26th, making Sweden the 32nd member of NATO. Some analysts believe that with Sweden's accession, NATO will complete the final puzzle of containment of Russia in the Baltic Sea, and the Baltic Sea will become the "NATO Lake". However, Russia has important outposts in this region and still possesses countermeasures. According to Agence France Presse, following Finland's accession to NATO last year, Sweden's accession to the treaty means that all countries surrounding the Baltic Sea, except Russia, will be included in NATO's territory, and the Baltic Sea will become a "NATO Lake". "Geographically, the Baltic Sea is becoming a lake in NATO," said Minna Aland, a researcher at the Finnish Institute of International Affairs. On April 22, 2023, people participated in protests in Stockholm, Sweden, protesting against large-scale international military exercises and opposing Sweden's accession to NATO. According to some analysts from Xinhua News Agency (photographed by Patrick Eckstrand), the formation of the "NATO Lake" has significant geopolitical significance for NATO. Sweden guards the long coastline of the Baltic Sea and also owns the largest island in the Baltic Sea, Gotland Island. After officially joining the treaty, Sweden will fully integrate into the NATO defense system, further strengthening NATO's defense posture in the Baltic Sea. Once a military conflict erupts with Russia, NATO has enough advantage to seize the space for Russia to maneuver along the Baltic customs key route. Sweden's accession will also help NATO reinforce vulnerable Estonia, Latvia, and Lithuania by sea during wartime. These three countries border Russia and have long been regarded as NATO's "Achilles heel". The underwater situation is unpredictable. Some analysts point out that although the strength of the Russian Baltic Fleet is far inferior to that of the Cold War era, Russia's surface and underwater forces can still pose a threat to NATO in this region. According to Agence France Presse, since the escalation of the crisis in Ukraine in February 2022, a series of events involving the Baltic Sea submarine pipelines and cables have sounded an alarm for the region, highlighting the complex and unpredictable underwater situation and exposing the fragility of the Baltic Sea seabed infrastructure. This aerial photo released by the Danish Ministry of Defense on September 27, 2022 shows a leakage point in the Nord Stream natural gas pipeline. In this context, some NATO countries are strengthening their naval deployment and seeking to improve their monitoring capabilities. Julian Pavlak, a researcher at the Federal Armed Forces University in Hamburg, Germany, pointed out that the ocean is different from land and monitoring is very difficult. The destruction of the Beixi pipeline and other incidents indicate that it is still difficult to accurately understand what has happened beneath and beneath the sea surface. Russia has a counter outpost, NATO is intensifying pressure on Russia's space in the Baltic Sea, but Russia has an important "outpost" in this region - Kaliningrad. This "enclave" is located between NATO member countries Poland and Lithuania. In recent years, the Russian side has strengthened its military deployment in Kaliningrad, including missiles capable of carrying nuclear warheads. Professor John Deny of the US Army Military Academy told Agence France Presse that Russia's military presence in Kaliningrad is not as large as during the Soviet era, but it has maintained its investment in underwater forces and continues to