Reports that Ottawa and Washington have resumed their delicate missile-defense discussions suggest that Canada may be ready to join the global missile-defense coalition. If so, it would be a welcome development.

The operative word here is 'global.' The missile shield now taking shape is a truly international missile defense (IMD) enfolding some of Canada's closest allies and oldest friends.

Let's start in Europe. In 2010, alliance leaders declared missile defense "a core element of our collective defense" and pledged to "develop the capability to defend our populations and territories against ballistic missile attack." Toward that end, Britain and Denmark have allowed modifications to early-warning radars to augment the missile shield. Spain is hosting a rotation of four Aegis missile-defense warships. Germany hosts a missile-defense operations center. Romania will host a land-based variant of the Aegis system, dubbed 'Aegis Ashore,' starting in 2015, as will Poland by 2018. Turkey hosts a powerful X-Band missile-defense radar, allowing the alliance to scan the horizon for threats from Iran.

Beyond NATO, U.S.-Israeli cooperation dating back to 1986 has yielded a sophisticated, layered defense against missiles, including the Iron Dome system, David's Sling system and Arrow anti-missile system. Israel also hosts an X-Band radar.

Likewise, Qatar hosts an X-Band radar. And the UAE recently became the first foreign government to purchase the U.S. terminal high altitude air defense system (THAAD).

Australia was an early adopter, signing a 25-year pact on missile-defense cooperation with the United States in 2004.

With a wary eye on North Korea, Japan deploys six Aegis ships, hosts an X-Band radar, with another on the way, and is co-developing a new interceptor missile for Aegis ships.

The United States has invested $157.8 billion on missile defense since 1985 an average of $5.6 billion per year. The dividend: thirty ground-based interceptors in California and Alaska, with 14 more on the way; two active THAAD batteries, with more scheduled to come online in 2013; 26 Aegis warships, building toward 36 by 2018.

Thanks to America's missile-defense investments, NATO has been able 'plug into' the existing missile-defense architecture for a relatively small amount, as NATO Secretary General Anders Fogh Rasmussen has explained, enabling the system "to defend European populations and territory from missile attack."

All told, 21 nations are directly participating in this networked system of systems. Yet Canada is not one of them. Given Canada's historic willingness to contribute to allied efforts from Normandy's beaches to NATO's founding, from the defense of Korea to the liberation of Kuwait, from Afghanistan to Libya it's jarring to scan the Missile Defense Agency's (MDA) growing list of international partners and not see Canada's name.

To be sure, support for missile defense, while widespread, is not universal. Russia is a vocal critic of NATO's missile defenses. Among 'the main external military dangers' identified by the Russian government are 'the creation and deployment of strategic missile-defense systems.' However, Moscow's opposition seems to have more to do with its inability to hold sway over Eastern Europe than with any real threat to Russian security. As then-Defense Secretary Robert Gates explained in 2010, "The Russians know that our missile defenses are designed to intercept a limited number of ballistic missiles launched by a country such as Iran or North Korea."

Testing Times
That brings us to the driving force behind the growing acceptance of missile defense: the burgeoning missile threat.

"If North Korea would be ready to attack the United States," Canadian Prime Minister Stephen Harper conceded in 2006, "that would be a risk for Canada's national security as well not only because of our common values, but because of our geographical proximity."

Given North Korea's technological advances and political unpredictability, that scenario seems more likely now than it was then, which may help explain reports of fresh missile-defense discussions between Washington and Ottawa.

Since 2009, North Korea has detonated two nuclear weapons, conducted long-range missile tests under the guise of satellite launches, threatened nuclear strikes against the United States, and demonstrated a threshold ICBM capability by lofting a satellite into orbit. Moreover, the Defense Intelligence Agency concludes "with moderate confidence" that North Korea "currently has nuclear weapons capable of delivery by ballistic missiles."

Likewise, the British government reported in 2011 that Iran has "been carrying out covert ballistic missile tests and rocket launches, including testing missiles capable of delivering a nuclear payload." Iran has tested a ballistic missile that brings targets in Europe within range. And the Pentagon reported in 2012 that "Iran may be technically capable of flight-testing an intercontinental ballistic missile by 2015."

The drive for long-range missilery by Tehran and Pyongyang is part of a larger missile-proliferation trend: Three decades ago, there were nine countries that fielded ballistic missiles. Today, there are 31.

The good news amidst this worrisome trend is that missile defense is no longer simply a theoretical possibility. In testing, missile defense has scored successes on 59 of 74 attempts 79.7 percent of the time. During a 2012 exercise, the system deflected four out of five "near-simultaneous representative threats," as MDA Director Vice Admiral James Syring reported last month. And in battle, missile-defense systems have protected population centers in Israel and military facilities in Kuwait.

If Canada decides to join the missile-defense team, Ottawa could contribute its voice to missile-defense decisions. Having a voice makes a difference, as Canada knows from participation in NATO. Canada’s voice helped guide a unified Germany into NATO after the Cold War, enhanced alliance deployments in Afghanistan and steered alliance operations over Libya.

Beyond wise counsel, Canada could join the Aegis missile-defense fleet, thus serving as an IMD force multiplier. Yet another way Canada could contribute is by dedicating facilities to the IMD effort, as Britain, Israel, Japan, Turkey and other allies have. In fact, Ottawa contemplated hosting an X-Band radar in northeastern Canada during an earlier round of missile-defense discussions.

"Canada", as former Canadian diplomat Paul Chapin has observed, "seems able to support missile defense for others, just not for itself." That may change in the months ahead. If nothing else, the enthusiastic embrace of missile defense in Europe and beyond should serve as political cover for Ottawa. Instead of sitting on the sidelines, Canadian policymakers can tell their ambivalent constituencies, "NATO made us do it."