Three countries with very different interests signed a remarkably ambitious agreement in Mecca earlier this month. Saudi Arabia, Turkey and Pakistan declared that an armed attack against any one of them would be considered an attack against all three.

That sounds consequential. Whether it actually is remains very much an open question.

The Mecca Joint Defense Agreement brings together Saudi money and regional influence, Turkey’s large and increasingly sophisticated military and defense industry, and Pakistan’s substantial armed forces — and, inevitably lurking in the background, its nuclear arsenal. It also reflects something Washington should find troubling: three longstanding American partners apparently believe they need additional security arrangements that do not depend upon the United States.

But there are potential benefits.

A credible regional defense arrangement could strengthen deterrence against Iran and its proxies and place more responsibility for regional security on countries that actually live in the region. Greater coordination on missile defense, intelligence, maritime security and protection of energy infrastructure could complement rather than undermine American interests. And anything that convinces Tehran that aggression will produce a coordinated regional response rather than isolated victims could contribute to stability.

The problem is everything we do not yet know.

Would Turkey really go to war with India on Pakistan’s behalf? Would Pakistan fight Iran to defend Saudi Arabia? Does the agreement extend to attacks by Iranian proxies? Does Pakistan’s nuclear deterrent somehow protect Saudi Arabia or Turkey? And how does NATO member Turkey reconcile this new commitment with its existing alliance obligations?

For Israel, the questions are even sharper. Recep Tayyip Erdogan has increasingly positioned Turkey as a regional rival of Israel. A security structure that expands Turkish military influence into Syria and the Gulf could eventually become considerably less benign than an arrangement designed principally to contain Iran.

There is also the larger American concern. Alliances are not simply military instruments; they are declarations about whom countries trust. If Saudi Arabia increasingly believes Washington is an unreliable security guarantor, it will continue looking elsewhere. That would make Saudi-Israeli normalization more difficult and reduce American leverage in a region where China and other powers are eager to expand theirs.

So watch what happens next.

Indeed, the first test arrived almost immediately. Just two days after the pact was signed, the Iran-backed Houthis claimed an attack on a Saudi Aramco refinery in Jazan. Does anything meaningful follow from Ankara or Islamabad?

Beyond that, watch for joint military exercises, integrated air and missile defenses, intelligence-sharing arrangements, permanent deployments and, most importantly, defense-industrial cooperation. Watch whether Egypt or other countries are invited to join. Watch what happens in Syria. And watch whether Saudi Arabia moves closer to Washington and Israel or uses its new alternatives to demand a substantially higher price.

For now, the Mecca agreement is more declaration than alliance. But declarations sometimes become institutions.
The U.S. and Israel should neither panic nor shrug. They should watch carefully for the moment when impressive words begin turning into military capability. That is when this treaty will tell us what it really is.