Israel possesses some 80 nuclear warheads — rather fewer than once thought, and lower than the nuclear arsenal of countries that are officially in possession of atomic weapons — according to the new 2013 yearbook put out by the Stockholm International Peace Research Institute (SIPRI), a leading think tank on global security issues.

Of those warheads, 50 are for medium-range ballistic missiles and 30 are for bombs carried by aircraft, the report said. In addition, “Israel may also have produced non-strategic nuclear weapons, including artillery shells and atomic demolition munitions,” the Guardian reported Monday.

Israel is not a signatory to the Nuclear Non-Proliferation Treaty and has long maintained an official position of ambiguity with regards to its nuclear capabilities.

In 1986, based on information supplied by ex-Dimona nuclear technician Mordechai Vanunu, later convicted of treason, the Sunday Times of London estimated that Israel had produced more than 100 nuclear warheads.

India and Pakistan, also countries that have not signed the NPT but that nonetheless possess nuclear weapons, each have around 90-120 warheads, SIPRI found, while the NPT countries have many hundreds, or, in the case of the US and Russia, many thousands, more.

Despite pledging not to do so, the countries that have signed the NPT are still developing new nuclear weapons technology and are prepared to hold on to their stores, the report said.

“All five legally recognized nuclear weapon states — China, France, Russia, the United Kingdom and the United States — are either deploying new nuclear weapon delivery systems or have announced programs to do so, and appear determined to retain their nuclear arsenals indefinitely,” SIPRI said in a press release, while noting that with the exception of China, which “seems to be expanding its nuclear arsenal,” overall numbers of nuclear weapons possessed by NPT countries have been falling.

At the start of 2013 the five NPT states, plus India, Pakistan and Israel, possessed “approximately 4,400 operational nuclear weapons. Nearly 2,000 of these are kept in a state of high operational alert. If all nuclear warheads are counted, these states together possess a total of approximately 17,265 nuclear weapons… as compared with 19,000 at the beginning of 2012,” SIPRI stated.

The report attributed the decrease to Russia and the US having reduced their inventories to fulfill their obligations under New START, the Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms, and the culling of obsolete weapons.

SIPRI does not count North Korea and Iran as nuclear powers, as their respective programs are still considered in their nascent stages.

“Once again there was little to inspire hope that the nuclear weapon-possessing states are genuinely willing to give up their nuclear arsenals. The long-term modernization programs under way in these states suggest that nuclear weapons are still a marker of international status and power,” SIPRI researcher Shannon Kile said.

The report, produced annually since 1968, analyzes issues relating to security and conflicts, military spending, the arms industry and non-proliferation, arms control and disarmament issues.

SIPRI found that in 2012, the numbers of peacekeeper forces deployed worldwide dropped some 10 percent, largely due to the gradual withdrawal of coalition forces from Afghanistan.

On Syria, “the United Nations appeared paralyzed… the new principle of an international responsibility to protect populations if the national government fails to do so — the basis of the 2011 intervention in Libya — was not invoked, as China and Russia threatened to veto any action through the UN and other Security Council members opposed outside ‘interference’ in Syria’s domestic affairs,” the report said.

“In the end, national interests and deep-rooted fears that the responsibility to protect undermines the principle of state sovereignty, seem to weigh heavier than the plight of populations caught up in conflict,” senior researcher Dr. Jaïr van der Lijn said.

Efforts to introduce international controls on cluster munitions were unsuccessful in 2013, the report said. Such devices disperse explosives that can sometimes detonate a significant amount of time after they are deployed, posing a threat to civilians.

Major arms-producing countries that have not signed onto the 2008 Convention on Cluster Munitions, including Israel and the US, continue to produce, distribute and stockpile such munitions, “even if most seem to have acknowledged their potentially grave humanitarian impacts,” SIPRI wrote.