RIGA, Latvia -- Russia will pay the price for meddling in the American election, a trio of U.S. senators warned Wednesday, Dec. 28, while visiting countries on the country's western border.

"We have all agreed to be pretty aggressive about an end to this Russian aggression," Sen. Amy Klobuchar, D-Minn., said about the Obama administration's claim that Russia hacked political groups' computers, including the Democratic Party, before the Nov. 8 election.

Klobuchar, Sen. John McCain of Arizona and Sen. Lindsey Graham of South Carolina are touring Estonia, Latvia, Lithuania, Ukraine, Georgia and Montenegro this week.

While assuring leaders of those countries that the United States will continue to support them and NATO, the senators took the opportunity while in the region to warn Russia, and President Vladimir Putin in particular.

Klobuchar said the three senators "are reinforcing our bipartisan commitment to strengthening our NATO alliances and are focused on major cyber security breaches which are of utmost importance as we learn of the depth of Russian interference in our recent election."

In a telephone interview with Forum News Service, Klobuchar said the three have learned from officials they visited that Russian cyber attacks have occurred in their region since 2007.

"It goes to the heart of democracy across the world," she said.

McCain and Graham, both Republicans, and other Senate leaders say they plan hearings on Russian computer attacks, even as president-elect Donald Trump downplays the issue.

"The key part is to respond," Klobuchar said. "Otherwise, they will keep doing it."

Without a response, she added, other countries like China also may attack American computers.

While criticizing Russia, the American lawmakers also were telling presidents, prime ministers and other officials they met that the United States will remain their ally.

"They love America in these counties," Klobuchar said, but Trump's comments such as one indicating he feels many counties do not pay enough for NATO has them worried.

The holiday visit shows "there is bipartisan support in Congress for places like Ukraine," Klobuchar said.

NATO members Latvia, Estonia and Lithuania, all ruled by Moscow in communist times, have been alarmed by Russia's annexation of Ukraine's Crimea peninsula in 2014 and its support for pro-Russian separatists in eastern Ukraine.

"It is now time for Russia to understand enough is enough," Graham said.

Graham promised action.

"There will be bipartisan sanctions coming that will hit Russia hard, particularly Putin as an individual," Graham said in the Latvian capital.

He did not elaborate further on what the sanctions could entail.

U.S. intelligence agencies have concluded that Russia tried to influence the Nov. 8 election by hacking individuals' and institutions' computers.

Russian officials have denied accusations of interference in the election.

The Estonian defense minister said his country is increasing its efforts to defend itself against cyber attacks after NATO recognized cyber attacks as an element of warfare, alongside land, sea and air.

In what Estonian officials say was a wake-up call, the country was hit by cyber attacks on extensive private and government Internet sites in 2007. State websites were brought to a crawl and an online banking site was closed.

Lithuania also said last week the Kremlin was responsible for cyber attacks that have hit government computers there over the past two years.