Paul Schulte was interviewed by World Politics Review's Global Insider about NATO's decision to reaffirm its commitment to its European-based arsenal of tactical nuclear weapons.

WPR: What is the current size and scope of NATO's nuclear weapons?

Paul Schulte: Some 160-200 U.S. B61 gravity bombs are understood to be deployed in Europe and Turkey, the remains of the alliance’s Cold War arsenal of 7,000 nonstrategic nuclear weapons (NSNWs). They are often called “NATO’s nuclear weapons," although the latest alliance Strategic Concept states that “The supreme guarantee . . . of security . . . is provided by the strategic nuclear forces” of the U.S., France and U.K., which are collectively much larger. The unique feature of NATO's European NSNWs is the system of "nuclear sharing," allowing nonnuclear allies to participate in nuclear planning and providing for certain NATO European air forces (currently Germany, Belgium, Netherlands and Italy) to deliver the B61s from their dual-capable aircraft (DCAs). The NSNWs’ value is contested, but proponents believe they strengthen the trans-Atlantic link with the U.S. strategic deterrent. This is of special importance to some Central and East European countries. Partly due to their concerns, present NSNW arrangements were confirmed at NATO's 2012 Chicago Summit, pending hoped-for negotiations to achieve reciprocal reductions in Russia's estimated arsenal of 3,700-5,400 NSNW.

WPR: Why are planned upgrades for NATO's nuclear weapons necessary, and how do they fit into the context of NATO's nuclear posture?

Schulte: The variable yield B61 bomb is the only remaining nuclear weapon in the U.S. Enduring Stockpile and the only one used in the nonstrategic role. It was first produced as long ago as 1968, and a Life Extension Program (LEP) is planned, the projected costs of which have recently risen to more than $5 billion. The LEP will extend service life; consolidate multiple variants into one modification; and improve safety, security and user control of the roughly 500 B61s. A new tail subassembly is intended to raise the B61's accuracy to latest standards.

Greater accuracy could permit smaller quantities of fissile material, lower yields, less radioactivity and more-precise and more-effective strikes against hardened targets. Especially if delivered by new stealth F-35 replacement DCAs, this would offer extra operational flexibility, facilitating future reductions in overall U.S. nuclear numbers. But critics argue it would be unnecessary and unavoidably provocative in Europe.

WPR: How is the nuclear weapon upgrade likely to be received by NATO members and non-NATO countries, particularly Russia?

Schulte: Those NATO members -- Germany, Benelux and Norway -- who would prefer U.S. NSNWs be withdrawn from Europe argue that America could spend its money better elsewhere, but they are unlikely to oppose the LEP openly, since it improves safety and security. The upgrade program will, however, increase domestic opposition from anti-nuclear groups. Moreover, Russian denunciation can be taken for granted, given Moscow's past statements insisting on total American nuclear withdrawal from Europe as a precondition for talks on NSNW arms control. This may make negotiations to reduce numbers, increase transparency or reposition NSNWs even less likely to succeed.

This article originally appeared in World Politics Review.