Which weapon marked the beginning of modern naval warfare?

The weapon that marked the beginning of modern naval warfare was the nuclear submarine.

Explanation:

In the 1950s, nuclear power partially replaced diesel-electric propulsion. This system was developed to also extract oxygen from seawater. These two innovations gave submarines the ability to stay submerged for weeks or months, and allowed for previously impossible trips, such as the crossing of the North Pole under the Arctic ice sheet by the USS Nautilus in 1958. Most of the military submarines built since that time in the United States and the Soviet Union have been propelled by nuclear reactors. The factors that limit the underwater permanence of these vessels are the food supplies and the psychological problems of a crew confined in such a limited space.  

Although the greater autonomy and performance of nuclear reactors means that these submarines are better for long-range missions or the protection of an aircraft carrier force, diesel-electric submarines have continued to be produced by countries with and without nuclear capability, as they can be harder to detect, except when you need to use your diesel engine to recharge the batteries. Technological advances in soundproofing, isolation and noise cancellation have substantially eroded this advantage. Much more limited in terms of speed and firepower, conventional submarines are also cheaper to build. The introduction of ships with anaerobic propulsion has caused a resurgence of this type of submarine.

answer: 1

explanation:

im pretty sure

roosevelt believed that in light of the country's recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. this belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of roosevelt's foreign policy.