Freedom of Navigation Operations are deliberate naval demonstrations to uphold that ships from any nation may transit international waters and airspace without undue interference. The point is to push back against claims that would restrict that movement, showing that those claims are not consistent with international law. In practice, a FONOP involves a ship or aircraft conducting a transit through waters or through an airway in a way that asserts the right of passage, even when a coastal state asserts a narrow territorial sea, extended baselines, or other zones that would limit innocent passage or transit. The goal is to keep global sea lanes open for all, based on customary international law and, where applicable, the principles of UNCLOS. This is why the best choice emphasizes challenging restrictive maritime claims and preserving freedom of navigation under international law. Live-fire exercises, domestic enforcement actions, or treaty negotiations are not the purpose of FONOPs.

Understanding hull classification symbols means reading the letters as a type plus propulsion. CV designates an aircraft carrier, and the suffix N shows nuclear propulsion. So CVN means an aircraft carrier powered by a nuclear reactor. This distinguishes it from older, non‑nuclear carriers (which would be CV) and from non-standard labels like “combat vessel” or “civilian vessel,” which aren’t used to describe Navy ships. Modern nuclear-powered carriers, such as the large fleet carriers, use this CVN designation.

The core idea here is momentum in the war at sea: two battles that decisively shift the balance from Japanese expansion to Allied offensive power, setting up the push toward Japan itself. Midway stands out because it stopped the Japanese carrier offensive and dealt a heavy blow to their carrier fleet. Losing four front-line carriers and many experienced pilots crippled Japan’s ability to project naval air power at scale, flipping the strategic initiative to the Allies. From that point, the United States could pursue an offensive strategy across the Pacific, building air and sea bases and choosing targets that would steadily erode Japan’s ability to wage war at sea. Leyte Gulf marks the other turning point by delivering a decisive defeat of Japanese sea power during the liberation of the Philippines. The battle demonstrated Allied dominance across combined arms—naval, air, and amphibious operations—while effectively eliminating Japan’s capacity to contest sea control in the Western Pacific. This victory opened the door for the invasion of the Philippines, cut Japanese lines of communication, and signaled the end of any hope for a return to strategic initiative for Japan in the Pacific. Other events in the options were important in their own right, but they don’t embody the same decisive shift in momentum. Pearl Harbor drew the United States into the war, but it didn’t reverse the tide. Guadalcanal was a crucial early campaign, but the war’s turning point comes with its later, more sweeping reversals. Coral Sea halted a Japanese advance and showcased carrier warfare, yet Midway more clearly changed the strategic balance. Iwo Jima and Okinawa showed intense fighting late in the war but did not reverse the overall momentum in the way these two battles did.

The big jump was nuclear propulsion. A submarine powered by an onboard reactor can run its electric motors for long periods without needing to surface for air or to recharge batteries, so it can stay submerged and cover vast distances. This dramatically increases endurance, which in turn enhances stealth because the vessel can remain hidden underwater rather than popping up to refuel or recharge. The first nuclear-powered submarine, demonstrated in the 1950s, showed that submarines could operate underwater for extended durations and travel across oceans, redefining both range and stealth. Diesel-electric improvements helped before, but they still required air to run the diesels and recharge batteries, limiting submerged time. Hydrogen fuel cells offered quiet power but didn’t deliver the same long-range, sustained underwater capability, and rotary propulsion systems don’t represent the major postwar breakthrough in question.