Over the last week, many Americans (and not a few Indians) have asked me why India does not “do a Gaza” on Pakistan, referring, of course, to an emulation of Israel’s punitive use of force against Hamas-run Palestine, a territory from which rockets rain down on Israeli soil with reliable frequency (if not reliable destructiveness … but that is not for want of Hamas intent).

My answer, given with the heavy heart that comes always with a painful grip on reality, is simple: India does not because it cannot.

Here are five reasons why:

1. India is not a military goliath in relation to Pakistan in the way Israel is to the Palestinian territories. India does not have the immunity, the confidence and the military free hand that result from an overwhelming military superiority over an opponent. Israel’s foe is a non-sovereign entity that enjoys the most precarious form of self-governance. Pakistan, for all its dysfunction, is a proper country with a proper army, superior by far to the tin-pot Arab forces that Israel has had to combat over time. Pakistan has nukes, to boot. Any assault on Pakistani territory carries with it an apocalyptic risk for India. This is, in fact, Pakistan’s trump card. (This explains, also, why Israel is determined to prevent the acquisition of nuclear weapons by Iran.)

2. Even if India could attack Pakistan without fear of nuclear retaliation, the rationale for “doing a Gaza” is, arguably, not fully present: Israel had been attacked consistently by the very force–Hamas–that was in political control of the territory from which the attacks occurred. By contrast, terrorist attacks on India, while originating in Pakistan, are not authored by the Pakistani government. India can– and does–contend that Pakistan’s government should shut down the terrorist training camps on Pakistani soil. (In this insistence, India has unequivocal support from Washington.) Yet only a consistent and demonstrable pattern of dereliction by Pakistani authorities– which would need to be dereliction verging on complicity with the terrorists–would furnish India with sufficient grounds to hold the Pakistani state culpable.

3. As our columnist, Karlyn Bowman, writes, Israel enjoys impressive support from the American people, in contrast to the Palestinians. No other state–apart, perhaps, from Britain–evokes as much favor in American public opinion as does Israel. This is not merely the result of the much-vaunted “Israel lobby” (to use a label deployed by its detractors), but also because of the very real depth of cultural interpenetration between American and Israeli society. This fraternal feeling buys Israel an enviable immunity in the conduct of its strategic defense. India, by contrast–while considerably more admired and favored in American public opinion than Pakistan–enjoys scarcely a fraction of Israel’s “pull” in Washington when it comes to questions of the use of force beyond its borders.

4. Pakistan is strategically significant to the United States; the Palestinians are not. This gives Washington scant incentive to rein in the Israelis, but a major incentive to rein in any Indian impulse to strike at Pakistan. However justified the Indian anger against Pakistan over the recent invasion of Mumbai by Pakistani terrorists, the last thing that the U.S. wants right now is an attack–no matter how surgical–by India against Pakistan-based terror camps. This would almost certainly result in a wholesale shift of Pakistani troops away from their western, Afghan front toward the eastern boundary with India–and would leave the American Afghan campaign in some considerable disarray, at least in the short term. So Washington has asked for, and received, the gift of Indian patience. And although India recognizes that it is not wholly without options to mobilize quickly for punitive, surgical strikes in a “strategic space,” it would–right now–settle for a trial of the accused terrorist leaders in U.S. courts.

5. My last, and meta-, point: Israel has the privilege of an international pariah to ignore international public opinion in its use of force against the Palestinians. A state with which few others have diplomatic relations can turn the tables on those that would anathematize it by saying, Hang diplomacy. India, by contrast, has no such luxury. It is a prisoner of its own global aspirations–and pretensions.

Tunku Varadarajan, a professor at the Stern Business School at NYU and research fellow at Stanford’s Hoover Institution, is opinions editor at Forbes.com, where he writes a weekly column.