Ash Carter, in a 42-page document prepared for the Senate Armed Services Committee, addresses issues from Russia to Afghanistan to cyber war to the US defense budget.
In the responses, obtained by Defense News, the nominee struck a forceful tone about Russia and its recent aggression in Ukraine.
"I reject the notion that Russia should be afforded a 'sphere of influence,' " Carter wrote. "If confirmed, I will continue to encourage US partners, such as Moldova, Georgia, and Ukraine, to build their security capacity and military interoperability with NATO."
Carter also said the US should maintain its lead role in "collective defense planning" among NATO allies, and that he would urge allies "to invest in military capabilities that that can impose costs on any opponent" while pushing large and small NATO allies to invest more money and resources "in capabilities that are needed by the alliance."
On Feb. 5, the alliance announced the formation of a 5,000-troop international "Spearhead Force" that would be supported by air, sea and special operations forces. The lead element of the brigade-sized force will be ready to deploy within 48 hours of getting the call, and the entire unit could move out within a week, NATO leaders said at a conference in Brussels.
All told, the NATO Response Force will number roughly 30,000 troops once it is fully fielded.
SASC Chairman John McCain, R-Ariz., told reporters last week that if members are collectively satisfied with the additional information supplied by Carter's answers, the panel could vote as soon as Tuesday to move his nomination to the Senate floor. The full chamber could confirm Carter by week's end before leaving on a week-long recess.
The 42 pages feature questions committee members did not have a chance to ask Carter during his hours-long confirmation hearing last Wednesday.
In response to Russia's violation of the Intermediate-range Nuclear Forces (INF) Treaty with the United States, Carter said Washington should consider further sanctions against Moscow and its economic interests.
The US "should consider a comprehensive strategy of diplomatic, economic, and military responses" to Russia's violations, since "Russia's continued disregard for its international obligations and lack of meaningful engagement on this particular issue require the United States to take actions to protect its interests and security as well as those of its allies and partners."
And if Russia fails to bring its policy back into line with the Cold War-era treaty, he insisted that the Pentagon should bolster US defenses against Russian weapons systems.
"The range of options we should look at from the Defense Department could include active defenses to counter intermediate-range ground-launched cruise missiles; counterforce capabilities to prevent intermediate-range ground-launched cruise missile attacks; and countervailing strike capabilities to enhance US or allied forces," Carter wrote. "US responses must make clear to Russia that if it does not return to compliance our responses will make them less secure than they are today."
He also opened a window into his thinking about acts of aggression in cyberspace.
Asked by one senator "when would you consider a cyber attack to be an act of war?" Carter replied that such a determination should be made "on a case-by-case and fact-specific basis."
He does offer some idea about potential red lines in his thinking, however.
"Malicious cyber activities could result in death, injury or significant destruction, and any such activities would be regarded with the utmost concern and could well be considered 'acts of war,' " he wrote, adding "an attack does not need to be deemed an 'act of war' to require a response."
Carter made a plea to lawmakers to make any cuts to the department's 2016 Pentagon budget plan via a back-and-forth with lawmakers.
"Should the Congress choose to appropriate only the amount allowed by the [2011 Budget Control Act] for FY2016, the Congress would make its own decisions on how to reduce the department's budget," he wrote. "My hope is that we would not face this alternative but, if we do, that those actions would be taken in consultation with the department."
A healthy chunk of his confirmation hearing was devoted to questions from SASC members about being candid with the president after two former Obama-era defense secretaries have publicly griped about White House micromanagement.
As he did during the hearing, Carter vowed to be honest with his boss. He promised to give President Barack Obama "my best strategic advice as to how to most effectively counter the [Islamic State] threat," adding he will "not hesitate to consider all options."
The nominee also reiterated his vow to advise Obama to make changes to his Afghanistan withdrawal plan should circumstances warrant such advice.
On the homefront, Carter issued a full-throated endorsement of the Navy's next-generation submarine program and promised to watch for deterioration of the US defense sector.
He called the Ohio-class replacement program "a vital component of our nuclear deterrence strategy."
And amid talk in some defense circles about paying for it outside the Navy's shipbuilding budget, Carter weighed in.
"The Ohio-replacement program will present challenges to the Navy's shipbuilding plan, particularly in the years after 2020," the nominee wrote. "The department needs adequate resources for modernization in order to insure we can make the transition to the new generation ballistic missile submarine.
"Which account it is funded in is of lesser importance. It makes the most sense to include the Ohio-replacement in the shipbuilding account but this is a decision that can be made in the future," he said. "If confirmed, I will work within the department and with the Congress to explore options to address this challenge."
On the industrial base, the former Pentagon acquisition executive said "healthy" US companies are "critically important to the department's long-term success." He promised to keep an eye on "risks" and to "preserve critical capabilities."
On China, Carter first noted the importance of diplomacy before stating "the United States should deter assertiveness in the region with a robust force posture, sustained presence, and commitment to building the capacity of its partners and allies."
Washington should "continue to modernize and strengthen its security alliances with Australia, Japan, the Republic of Korea, Philippines, and Thailand," he told the committee. "The United States should also deepen relationships with and among its partners in South and Southeast Asia to build capacity and reduce vulnerabilities."
With Moscow re-asserting itself in eastern Europe, Carter told the panel he would "work personally to encourage all [NATO] allies to meet" their promises.
"I would urge allies with larger economies to invest in military capabilities that that can be used to impose costs on any opponent with minimal cost and risk to alliance forces," Carter wrote to the lawmakers. "For allies with smaller economies, I would encourage them to invest in capabilities that are needed by the alliance, and in which they may have a comparative advantage."