WASHINGTON — The United States announced a new round of military aid for Ukraine worth more than $2.6 billion to help the country prepare for intensified Russian attacks in the coming months, the Pentagon said Tuesday.

Since Russia invaded Ukraine in February 2022, the U.S. has committed more than $35 billion in security aid. The aid announced Tuesday is split into two portions — $500 million in immediate aid and $2.1 billion in equipment that Ukraine will receive in the next several months.

The Pentagon said the two aid packages reflect the U.S. commitment to its ongoing support of Ukraine’s war effort and focus on three areas of need — air defense, ammunition supplies and armored vehicles.

“Our focus is on supporting the Ukrainians and changing the dynamic on the ground,” said a senior defense official who spoke on condition of anonymity. “The war is at an important stage.”

For the first time, Ukraine is getting several counter-drone 30mm gun trucks, which can detect and intercept sophisticated unmanned drones like the ones that Iran has given to Russia. The Ukrainians will also get a number of refueling trucks and tactical vehicles that can recover equipment in the field.

Some of the thinking behind the new aid, the defense official said, is focused on giving Ukraine a “layered and integrated approach to air defense.” Many of the Russian attacks in the past 14 months have been in the form of missiles and other aerial munitions.

The new aid also provides Ukraine a “steady flow” of artillery rounds and ammunition, spare parts, maintenance components, and expanded U.S.-led training in combined arms and joint maneuver operations, the official said.

Included in the $500 million portion is ammunition for various weapons systems, including the Patriot air defense system, the High Mobility Artillery Rocket Systems, or HIMARS, and missiles that are tube-launched, optically tracked and wire-guided.

That aid is being provided through the presidential drawdown authority, which allows the Pentagon to take the items from the Defense Department stocks and ship them to Ukraine on an emergency basis.

Ukraine has so far been given three Patriot air defense systems — one each from the U.S., Germany and the Netherlands — and Ukraine troops have recently completed training at Fort Sill, Okla., on how to use the sophisticated missile system.

The remaining $2.1 billion in aid is being given through the Ukraine Security Assistance Initiative, a program that procures the items from manufacturers. Most equipment pledged through the initiative takes longer to reach Ukraine because they need to be built. The M1 Abrams tanks that the U.S. has committed to Ukraine, for example, are being provided through the initiative and aren’t expected to arrive in Ukraine until late 2023 or early 2024.

Included in the initiative portion of the aid is what the Pentagon called “a significant package of air-defense capabilities,” such as the new gun trucks, munitions for National Advanced Surface-to-Air Missile Systems, air-surveillance radars, armored bridging systems and mobile laser-guided rocket systems.

Defense Secretary Lloyd Austin and President Joe Biden have said repeatedly that the United States will help Ukraine defend its homeland for as long as Russia keeps up its attacks, some of which have targeted civilians and non-military infrastructure.

For weeks, the U.S. and its allies have been working with Ukraine to prepare for intensified Russian attacks as the weather has become increasingly warmer.

“We want to help Ukraine advance and hold its position in what we expect will be a Ukrainian counteroffensive,” the defense official told reporters Tuesday.

Tuesday’s new round of aid came on the same day that Finland became the 31st member of NATO, which expands the defensive alliance’s eastern flank along Russia’s border. From the beginning, Moscow has said it considers NATO expansion an existential threat. Sweden is also set to join the alliance soon.

“Finland is one of the highest [dollar value] contributors to Ukraine,” the senior defense official said. “The package we are announcing today will complement many of the capabilities our allies and partners are providing.”

Sweden had intended to join NATO at the same time as Finland, but Turkey has slowed the process — mainly because it argues that Sweden has given sanctuary to people Turkey claims are Kurdish militants. Ukraine has also applied to join NATO but has not yet received a formal invitation.