CARACAS, Venezuela — Venezuela’s embattled government, increasingly alienated from its Latin American neighbors, has been doing business with US-blacklisted Russian companies, allowing Moscow to shore up its influence in the Western Hemisphere and raising bipartisan concern in Congress.

State oil company Rosneft, Gazprombank, the third-largest bank in Russia, and the military manufacturer Rostec were added to the US Treasury’s Office of Foreign Assets Control sanctions list in 2014 in response to Moscow’s support for rebels in Ukraine and annexation of Crimea.

Since then, Russia and Venezuela, two of the US’ main adversaries, have grown closer as the two have looked for ways to pull themselves out of the economic doldrums.

“There is cooperation at the highest strategic levels with Russia, not only in the energy, military, industrial and agricultural areas, but also in the political area,” Venezuela’s Foreign Minister Delcy Rodríguez told BuzzFeed News on Saturday.

Rodríguez's Russian counterparts echo that sentiment. There is “a new impetus to the entire range of Russian-Venezuelan relations,” the Russian Ministry of Foreign Affairs said in a statement in February, four months after the presidents of both countries met in Istanbul. According to the statement, there is an “intensive dialogue” between the two countries.

Venezuela is also working with energy exporter giant Inter Rao, which is not on the US’ blacklist.

The ties between Caracas and Moscow, strong under former Venezuelan president Hugo Chávez, have picked up a second wind under President Nicolás Maduro as Russia looks for markets outside the US’s influence that are unconcerned with the difficulty in dodging American sanctions. That in turn has begun to stir worries in Washington.

Sens. Ben Cardin and Marco Rubio introduced legislation addressing the crisis in Venezuela on Wednesday, including new financial sanctions on individuals “responsible for undermining democratic processes” and providing $10 million in humanitarian aid to the Venezuelan people.

The senators expressed concern over the transaction between Venezuela’s state-run oil company PDVSA and Rosneft. Rosneft might walk away with a 49.9% stake of Citgo, a US-affiliate of PDVSA, if the troubled Venezuelan oil giant defaults.

On Thursday, two members of the House Foreign Affairs Committee, ranking member Rep. Eliot Engel and former chairwoman Rep. Ileana Ros-Lehtinen, sent a letter to President Donald Trump urging him to push for a review of the situation in Venezuela at the United Nations Security Council.

As Venezuela spirals further into autocratic rule, growing insecurity, and a protracted shortage of food and medicine, pressure from governments in the Western Hemisphere to restore democracy continues to deepen, further alienating the oil-rich nation from the rest of the world. Rodríguez announced last week that Venezuela is withdrawing from the Organization of American States, which includes all 35 countries in the Western Hemisphere.

Sustained protests against Maduro’s rule intensified after the Supreme Court temporarily stripped Congress of its powers in March. Opposition leaders said the ruling intended to give Maduro the power to create joined oil ventures without congressional approval.