Ukraine’s military had only one Bohdana artillery cannon in its arsenal when Russia invaded the country two years ago. Yet that single weapon, built in Ukraine in 2018 and able to shoot NATO-caliber rounds, proved so effective in the earliest days of the war that it was trucked to battlefields across the country, from the northeastern city of Kharkiv to the southwestern coast along the Black Sea and points in between.

Now, Ukraine’s arms industry is building eight of the self-propelled Bohdana artillery systems each month, and although officials will not say how many they’ve made in total, the increased output signals a potential boom in the country’s domestic weapons production.

The ramp-up comes at a pivotal moment. Russia’s war machine is already quadrupling weapons production in round-the-clock operations. Ukraine’s forces are losing territory in some key areas, including the strategic eastern town of Avdiivka, where they withdrew from in February. A U.S. aid package is still hung up in Congress. And while European defense firms are gingerly opening operations in Ukraine, major American weapons producers have yet to commit to setting up shop in the middle of a war.

It is widely agreed that Ukraine needs to rebuild its domestic defense industry so that its military will not have to rely for years to come on the West, which has at times hesitated to send sophisticated weapons systems — including air defenses, tanks and long-range missiles. Whether that can be done in time to alter the trajectory of a war that would be all the more tenuous without more U.S. military aid remains to be seen.

But Ukraine’s military engineers have already shown surprising skill in jury-rigging older weapons systems with more modern firepower. And over the last year alone, Ukraine’s defense companies have built three times as many armored vehicles as they were making before the war and have quadrupled production of anti-tank missiles, according to Ukrainian government documents reviewed by The New York Times.

Funding for research and development is forecast to increase by eight times this year — to $1.3 billion from $162 million — according to an analysis of Ukraine’s military budget through 2030 by Janes, a defense intelligence firm. Military procurement jumped to a projected 20-year high of nearly $10 billion in 2023, compared with a prewar figure of about $1 billion a year.