By Gregory Poling & James Hurndell

New Zealand’s prime minister, John Key, on February 24 made the long-awaited announcement that his government will join the U.S.-led coalition fighting the Islamic State in Iraq and Syria (ISIS). New Zealand will deploy 143 soldiers, alongside hundreds of Australian troops, to Iraq on a noncombat mission to train the Iraqi army. The combined force is expected to head to Iraq in May. Key said that after nine months, his government will decide whether to continue the deployment, which could last a maximum of two years.

New Zealand has been under mounting pressure to join the coalition, which includes all its partners in the “Five Eyes” intelligence-sharing group—Australia, Canada, the United Kingdom, and the United States—among others. The slow, cautious deliberations in Wellington over whether and how to join the anti-ISIS coalition might have seemed excessive in Canberra and Washington. New Zealand did after all contribute to the earlier U.S.-led coalitions in Afghanistan and Iraq, and in the case of Iraq did so even after opposing the U.S. invasion. But patience was warranted.

New Zealand’s contribution will prove valuable on the ground and lends further legitimacy to the already-broad coalition. It also highlights the complicated balance that must be struck in many nations that are strong partners of the United States, but face significant public opposition to foreign military entanglements following a decade of what they perceive as U.S. adventurism abroad.

New Zealand’s limited capabilities and domestic politics required a more considered and cautious approach than that taken by its Australian counterpart, whose air force flew its first combat missions against ISIS on October 6 and which deployed hundreds of support personnel and special forces soldiers later that month. Prime Minister Key consistently reiterated that New Zealand must play a role in taking on ISIS, though only through noncombat training activities. The time needed to translate that high-level political will into tangible action reflects the constraints of New Zealand’s military capabilities and public opinion.

After a long deployment in Afghanistan, via the Bamiyan Provincial Reconstruction Team, New Zealand public opinion shows an understandable level of fatigue with foreign deployments. A recent TV3-Reid Research Poll showed just 50 percent of the public in favor of a noncombat contribution to the coalition, which put pressure on the government to make a strong public case and carefully manage risk.

The New Zealand Defence Force is limited to ground operations due to lack of a combat air wing. Once deployed, it can provide some of its own force protection, but it must depend on larger coalition partners for security and logistics. The low public tolerance for casualties places a premium on troop safety, but even when remaining away from the front lines as trainers, New Zealand forces still face the risk of casualties, as evidenced by the experience of coalition troops in Afghanistan. These factors played a key role in defining New Zealand’s limited commitment to building the capacity of the Iraqi army.

Iraq’s foreign minister, Ibrahim al-Ja’afari, traveled to New Zealand on February 13 and made a formal request for assistance in the fight against ISIS. This direct request from Iraq helped dilute the narrative that the United States was dragging New Zealand into another foreign conflict. Instead, it lent credence to the government’s argument that it had an obligation to fulfil, within limits, in the fight against ISIS. As such, it gave Key additional political space to commit to helping build capacity in Iraq.

New Zealand can bring a wealth of experience in capacity-building missions as well as further credibility to the U.S.-led coalition. The time the decision took reflects neither indecisiveness nor a lack of willingness on the part of the government. Instead, it reflected the political necessities placed on Wellington by its capabilities, status as a partner but not security ally of the United States, and a skeptical public.

If it rushed a decision and, as a result, poorly managed the political and security risks involved, New Zealand’s government could have poisoned the public against both the present and any future U.S.-led security operations. Instead, the careful approach to joining the fight, and the lack of overt U.S. demands that it do so, will make New Zealand a more resilient partner for the United States as the two nations embark on a new era of security cooperation.

Mr. Gregory B. Poling is a Fellow with the Pacific Partners Initiative at CSIS. Follow him on twitter @GregPoling. Mr. James Hurndell is a researcher with the Pacific Partners Initiative.