The United States toughened sanctions against Russia Thursday, dashing Russian hopes they might soon be lifted.

The expanded U.S. Treasury list targets 15 individuals and entities, adding the son of a billionaire ally of Russian President Vladimir Putin and a sovereign wealth fund to combat Russian efforts to circumvent restrictions.

The updated sanctions list is "designed to … to further align U.S. measures with those of our international partners, and to provide additional information to assist the private sector with sanctions compliance," the U.S. Office of Foreign Assets Control said in a statement Thursday.

"Our attitude towards such U.S. sanction activities is well-known, it has not changed," said Kremlin spokesperson Dmitry Peskov Friday. "We consider the sanctions to be illegal; they violate the rule of international law, they harm bilateral relations." He added that Moscow might respond asymmetrically to the expanded sanctions, Sputnik reported.

The move comes a day after Russia vetoed a United Nations Security Council resolution. The resolution would have created an international tribunal to try suspects in the Malaysian airliner downing that killed 298 passengers in eastern Ukraine last year. The U.S. and its allies believe that pro-Russian separatists shot down the plane with a Russian missile, although Putin continues to deny Russia's involvement.

The U.S. and European Union first imposed sanctions on Russia after Moscow backed separatists in Ukraine. Thursday's move signals "the long-term nature of the sanction environment for Russia," commented Dmitry Dolgin, a bank analyst in Moscow, to Reuters Friday.

However, spokesmen for the Russian state development bank VEB and Russian state fund RDIF said the expanded list would have little effect as it was "essentially a technical repetition" of the last year's sanctions, RDIF said in a statement to Reuters.

"The new U.S. sanctions will not have a significant effect on VEB group's operations," said a spokesman for the Russian state development bank, whose subsidiaries were among the additions to the list. He said the bank had already been under U.S. sanctions imposed last year. "The new sanctions list is only clarifying the previous statement ... - VEB's units are listed by name."

The U.S. and the European Union's relationship with Russia soured last year after Russia annexed Crimea and Ukrainian President Viktor Yanukovych was removed from office. The U.S. and the EU have limited some Russian companies' access to borrowing and barred technology transfers to energy producers in response to Russian support for a separatist insurgency in eastern Ukraine. A ceasefire agreed in Minsk earlier this year has been repeatedly violated by the Russian-backed separatists, according to the U.S. State Department.