Donald Trump meets Vladimir Putin at the opening of the G20 summit on July 7, 2017 in Hamburg, Germany.

The Trump administration said on Monday it would not immediately impose additional sanctions on Russia under a new law designed to punish Moscow's alleged meddling in the 2016 U.S. election, insisting the measure was already hitting Russian companies.

"Today, we have informed Congress that this legislation and its implementation are deterring Russian defense sales," State Department spokeswoman Heather Nauert said in a statement.

"Since the enactment of the ... legislation, we estimate that foreign governments have abandoned planned or announced purchases of several billion dollars in Russian defense acquisitions."

The administration faced a deadline on Monday to impose sanctions on anyone determined to conduct significant business with Russian defense and intelligence sectors, already sanctioned for their alleged role in the election.

But citing long time frames associated with major defense deals, Nauert said it was too soon to tell how effective the law had been, so it was better to wait to impose those sanctions.

"From that perspective, if the law is working, sanctions on specific entities or individuals will not need to be imposed because the legislation is, in fact, serving as a deterrent," she said in a statement.

President Donald Trump's administration also did not make public reports required by Monday under the bill he reluctantly signed into law on Aug. 2, just six months into his presidency.

The measure, known as the "Countering America's Adversaries Through Sanctions Act," or CAATSA, required the administration to list "oligarchs" close to President Vladimir Putin's government and issue a report detailing possible consequences of penalizing Russia's sovereign debt.