What instrument of National Power is utilized by the Department of State for establishing military access and forming partnerships?

The correct choice is the diplomatic instrument of national power. The Department of State plays a critical role in establishing military access and forming partnerships through diplomatic means. Diplomacy involves negotiations, treaties, and agreements that lay the groundwork for military cooperation and access to facilities or resources in other nations.

Through diplomatic channels, the Department of State can coordinate with foreign governments to facilitate joint exercises, security partnerships, and access to military bases, thereby enhancing the United States' ability to operate internationally and respond to global security challenges. The diplomatic approach is essential in building trust and collaboration with allies and partners, ensuring that military actions can be supported by a solid political foundation.

In contrast, while military instruments represent the actual use of force and capabilities, they are often a last resort and follow the foundations laid by diplomatic efforts. Economic instruments involve trade and financial engagements that can support or incentivize certain diplomatic or military partnerships, and informational tools relate to the dissemination of information and influence, which, while significant, do not directly establish access or form military partnerships in the same manner as diplomacy does.