WASHINGTON (Nexstar) — On Tuesday, President Biden visited a Lockheed Martin plant in Alabama that manufactures javelin missiles that the U.S is providing to Ukraine.

Biden praised the employees who make the missiles.

“Those javelins I saw, there’s 10 for every tank that there is in Ukraine right now. You’re changing people’s lives,” Biden said. “I came to say thank you, thank you, thank you.”

The U.S. has shipped thousands of javelins, stingers and howitzers to Ukraine, but the steady shipments of weapons come with a cost to the country’s stockpile.

Analysts estimate that the U.S. has shipped about one-quarter of its stingers and one-third of its javelins to Ukraine.

Defense Secretary Lloyd Austin says he’s optimistic manufacturers will increase production, but a shortage of semiconductors may prevent that since each javelin requires more than 200 domestic chips.

“Boosting domestic chip manufacturing isn’t just critical to making more in America or lowering prices, it’s also a vital component of our national security,” White House Press Secretary Jen Psaki said.

President Biden urged Congress to quickly approve more funding to help Ukraine and boost domestic production of semiconductors.

“This fight is not going to be cheap. But caving to aggression would even be more costly,” Biden said.