Leaked Defense Department documents reveal possible weak links in Ukraine’s military campaign against Russian forces, warning that kyiv could run out of crucial air defense missiles by May.

Under relentless attack from Russian missiles and drones, Ukraine is using vast amounts of air defense munitions, including Russian-made BUK and S-300 systems, according to two allegedly secret Pentagon documents, among a trove of troves that have surfaced online. .

If Ukraine is unable to bolster its air defense munitions supplies in time, Russia could potentially secure air superiority and start flying fighter jets over areas held by Ukrainian troops, according to one of the two documents, dated February 28. .

Such a scenario could alter the outcome of the war in Russia’s favor, military analysts say. So far, neither side has been able to achieve the upper hand in the air and Russian planes generally avoid venturing into Ukrainian-controlled airspace, analysts say.

NBC News obtained more than 50 of the leaked documents.

A Pentagon team is looking into the veracity of the documents and the potential impact of the disclosure, spokesman Chris Meagher told reporters on Monday.

“The Department of Defense is working around the clock to analyze the scope and scale of the distribution, the assessed impact, and our mitigation measures,” Meagher said.

The documents appear to contain «sensitive and highly classified material,» he said.

A senior US official previously said the government’s «working theory» is that the documents are real but some may have been altered.

According to two of the documents marked «secret» and dated February, Ukraine faces a looming shortage of Russian-made air defense missiles without sufficient deliveries of similar systems from NATO countries.

“Ukraine’s ability to provide medium-range air defense to protect the FLOT (front line of troops) will be fully reduced on May 23,” one of the documents states.

Ukraine is balancing the need to protect critical infrastructure, population centers, frontline troops and other key assets in Ukraine with limited resources, it says.

Russian-made SA-10 and SA-11 missiles comprise 89 percent of Ukraine’s air defense protection for medium to long-range threats above 20,000 feet, it says.

Supplies of the BUK SA-11 missiles will be completely depleted by Thursday at the current rate, the S-300 by May 3 and the shorter-range SA-8 by May, according to a chart in one of the documents. The same chart predicts that US-made NASAMs will sell out on Friday.

Under that scenario, Russian bombers could have «freedom of aerial maneuver» and Russian planes could attack Ukrainian ground forces or other targets without having to rely on drones or cruise missiles, according to the documents.

Ukraine could then lose the ability to resupply its troops from planes or helicopters or to concentrate its ground forces along the front line or for a possible counteroffensive, one of the documents says.

To help Ukraine maintain its air defenses, kyiv’s forces could alter their tactics to conserve their ammunition and employ «military deception,» according to the documents. Western countries could also offer more air defense systems, including US-made Patriot and NASAM batteries.

Another leaked document described the burn rate of HIMARS long-range rocket systems that the US provided to Ukraine, information that could be of interest to Russia. But the documents do not offer a forecast of when the ammunition will run out.

Daily Russian airstrikes could gradually weaken Ukraine’s air defenses, according to Western analysts and a US military official. US and NATO allies have pledged to provide Kiev with more air defense systems and munitions, and Washington has promised to deliver additional Patriot missile batteries.

A study conducted last year by the Royal United Services Institute, a UK-based think tank, warned that Western countries urgently needed to bolster Ukraine’s air defenses or risk seeing Russia operate with impunity in the air.

Russia’s failure to destroy Ukraine’s mobile air defense missiles has prevented Moscow from using its large air force of bombers and fighter jets to hit key targets and Ukrainian troop positions, according to the report.