U.S. lawmakers are alarmed that Russian efforts to weaken or lift economic sanctions imposed following its invasion of Ukraine could be bearing fruit following a high-level meeting with Italy's top diplomat.

"For sanctions to be effective, it is critical for the United States and its European allies to maintain a united front," Sen. Rob Portman, R-Ohio, a member of the Senate Foreign Relations subcommittee that focuses on European and Russian policy issues, told the Washington Examiner.

Portman offered that exhortation after Russian Foreign Minister Sergey Lavrov hosted Angelino Alfano, his Italian counterpart, at a meeting in Moscow to discuss political ties between the two countries. Although reversing "the unprecedented growth of international terrorism" was a major agenda item, Lavrov emphasized most of all the potential for renewed trade between the two countries — a potentially significant diplomatic victory for the Russians, who want Western powers to overlook the 2014 annexation of Crimea and ongoing violence in eastern Ukraine.

"Unfortunately, our trade has plunged 60 per cent over the past three years," Lavrov said Monday. "We have similar views on the role of energy in the consistent development of our relations. We exchanged opinions on the possible involvement of Italian companies in various gas pipeline projects, which aim to strengthen Europe's energy security."

Russian President Vladimir Putin also broached the topic of energy deals with Japan, but the U.S. ally vowed not to weaken international sanctions imposed by the G7 — a group of seven Western democracies that account for over 40 percent of the global economy, according to the Council on Foreign Relations. If Italy, the titular chair of the G7 in 2017, were to abandon the sanctions or weaken them by boosting trade, that would undermine the effectiveness of the sanctions as a whole and make it more likely that other countries lift them as well.

"Putin is going to try to undermine the sanctions regime, time and time again, and the NATO countries have to be smart to avoid his nonsense," New York Rep. Eliot Engel, the top Democrat on the House Foreign Affairs Committee, told the Washington Examiner. "Now there are going to be times where countries are going to do . . . things that we think are ridiculous. And that's what's happening here."

Renewed trade with a Western power would be useful to Putin now, as he is facing intense protests against political corruption at home. As the Lavrov-Alfano meeting took place just several weeks after intense fighting in eastern Ukraine, it could encourage the Russians to continue to violate the Minsk ceasefire agreements that were supposed to bring stability to the area.

"As the president has said, it is too early to talk about lifting any of our sanctions against Russia," a State Department spokesman told the Washington Examiner. "Our sanctions remain in place, and we are prepared to provide relief when Russia fully implements its commitments pursuant to the Minsk agreements."

Portman concurred. "Any actions that undermine this unity are unhelpful at a time when Russia is still not living up to its commitments under the Minsk ceasefire agreements," he said. "Any discussion on lifting sanctions must be put off until then."

Italy's Alfano maintained that sanctions relief should be tied to the success of the ceasefire, according to Russian reports, but the visit also might suggest that his country is uncomfortable with the ongoing strategy of isolating Russia.

"My visit takes place within a broader scenario of high-level talks and testifies Italy's interest in maintaining and enhancing the dialogue with Russia, a country we historically consider to be a neighbor and a friend," he said. "We are, in fact, convinced that the international community cannot disregard a dialogue with Moscow, especially on the major international crises and global challenges which undermine our security."

Engel warned that any economic pacts struck any energy agreement would diminish the effectiveness of the international sanctions even if they didn't violate the letter of the measures.

"The way you're going to change behavior in Russia is if you make Putin pay for it," Engel said. "And you don't make him pay for it if the alliance starts breaking up."