WASHINGTON (AP) — The U.S. will provide an additional $1.1 billion in aid to Ukraine, with funding for about 18 more advanced rocket systems and other weapons to counter drones that Russia has been using against Ukrainian troops, the Biden administration announced Wednesday.

The latest package is being provided under the Ukraine Security Assistance Initiative, which funds contracts to purchase weapons and equipment. And it brings the total of U.S. aid to Ukraine to nearly $17 billion since the Biden administration took office.

The aid announcement comes as Russia moves to annex parts of Russian-occupied Ukraine that held Kremlin-orchestrated referendums on living under Moscow's rule. The votes were denounced by Kyiv and the West as illegal and rigged.

"We will not be deterred from supporting Ukraine, we will continue to stand with the Ukrainian people, and provide them with the security assistance they need to defend themselves, for as long as it takes," White House press secretary Karine Jean-Pierre said.

Since the funding is for contracts for weapons and equipment, it is aimed at helping Ukraine secure its longer-term defense needs. It could take a year or two for Ukraine to get the systems. The U.S. has used Pentagon drawdown authority to provide weapons more immediately, and another announcement for that Defense Department aid is expected early next week.

The package includes funding for 18 of the High-Mobility Artillery Rocket System, or HIMARS, and ammunition for them, and 12 Titan systems, which are used to counter drones. Officials have said the HIMARS and other similar systems were key to Ukraine's battle successes in recent weeks. And the Russians have been using Iranian-made drones to target Ukrainian forces, underscoring the need for more systems to counter that threat.

Also in the package is funding for about 300 vehicles, dozens of trucks and trailers to transport heavy equipment, a variety of radars, communications and surveillance equipment, and other gear for soldiers. It also will include funding for equipment to detect explosives and for maintenance and training.

The war, now in its seventh month, has shifted to a new phase, as Russia tries to rebound from recent combat losses and use the referendums to politically solidify the gains it had made in the four occupied regions in the south and east.

Pro-Russia officials in Ukraine's Donetsk, Kherson, Luhansk and Zaporizhzhia regions said Wednesday they would ask Russian President Vladimir Putin to incorporate their provinces into Russia. It wasn't immediately clear how the administrative process would unfold.

Jean-Pierre said the U.S. has determined that Russia falsified the results of the referendums, which it said showed overwhelming support for annexation.

"These so called referenda have been an exercise in coercion and disinformation, executed by puppet authorities following orders from Russia," she said.

Jean-Pierre signaled that the White House was preparing new sanctions against Russia in response to the referendums, saying the U.S. and its allies planned to impose a "severe economic cost on Russia when they move forward with annexation."