Here's a simple investment thesis: when you fire a hundred expensive missiles, you eventually have to buy more. That basic logic was on full display Monday as defense-focused exchange-traded funds (ETFs) moved higher, reacting to recent military strikes. The story isn't just about the headlines; it's about the industrial and budgetary machinery that kicks in afterward.

"It's notable that more than 100 Tomahawk missiles were reportedly launched on the first night alone. With roughly 4,000 in the U.S. arsenal, that level of usage underscores the likelihood of increased replenishment, production, and defense spending going forward. We're already seeing that reflected in the market, with defense stocks trading higher this morning," noted Tony Bancroft, portfolio manager for the Gabelli Commercial Aerospace and Defense ETF (GCAD).

Think about it. If you have a stockpile of 4,000 of something and you use over 100 in a single operation, that's a meaningful dent. Someone, somewhere, is going to get an order to make more. That's the kind of predictable, multi-year contract work that defense contractors—and their investors—love.

The $1.5 Trillion Backdrop

This replenishment story isn't happening in a vacuum. It's playing out against a fiscal backdrop so large it's almost hard to comprehend. "The U.S. defense budget is approximately $1.5 trillion — an extraordinarily large figure. Even a fraction of that amount would still exceed most current projections for fiscal year 2027," says Bancroft.

But it's not just a U.S. story. The international picture adds another layer. Bancroft points out that if NATO allies (excluding the U.S.) were to hit a procurement target of 3.5% of GDP, that would translate to about $400 billion in annual defense spending. "Importantly, our allies have materially increased their defense budgets over the past several years, and we expect that upward trend to continue," he says.

And here's the kicker for U.S. markets: a lot of that money is likely to flow back to American companies. "The United States remains the dominant force in global defense," Bancroft said, citing the country's expansive industrial base. Europe and other allies often face capacity constraints, meaning when they need to buy advanced systems, they frequently turn to U.S. suppliers. This positions U.S. firms as the primary beneficiaries of a global spending uptick. Companies like L3Harris Technologies Inc (LHX) have already raised their international sales outlook for the coming year.

How to Play the Arsenal Trade

For investors, the move isn't just about picking individual contractor stocks. ETFs offer a way to get broad exposure to the entire aerospace and defense sector. Beyond the Gabelli ETF (GCAD), there are well-known funds like the iShares U.S. Aerospace & Defense ETF (ITA) and the SPDR S&P Aerospace & Defense ETF (XAR). These funds hold the major contractors that stand to gain from these long-term procurement cycles.

The critical distinction for investors is between short-term noise and long-term trends. Geopolitical events can create brief spikes in defense stock prices that quickly fade. But replenishment contracts and structural increases in defense budgets are different. They involve years-long lead times, firm orders, and predictable revenue streams. They are the antithesis of a fleeting headline.

So, the real question isn't whether defense stocks went up on Monday. It's whether this week's rally is a short-term reaction or the early, market-recognized phase of a deeper, budget-fueled cycle. When you combine the immediate need to replace what's been used with a $1.5 trillion budget and rising global demand, the argument for a longer-term story starts to look pretty solid. It's the economics of the Tomahawk: fire enough of them, and the financial fallout can be just as impactful as the explosive kind.