A top Russian official recently declared: "There's no country in the world that Russia has worse relations with than Latvia."
By Steve Rosenberg
BBC Moscow correspondent
The two countries are squabbling over borders, arguing about human rights and clashing over the past.
Washington is building ties with former Soviet republics
US President George W Bush, though, says he is looking forward to his trip to the region.
So why has the US president decided to visit to Russia's most troublesome neighbour now?
It has a lot to do with sending messages to Moscow.
By visiting Riga and by meeting with the presidents of Latvia, Lithuania and Estonia, Mr Bush will show his solidarity with their view of history - one very much at odds with Moscow's.
Russia sees itself as the main power which helped bring freedom to Europe, defeating the Nazis at an enormous human cost - 30m Soviet lives were lost.
But the Baltic countries see the Soviet Union as an aggressor.
They recall the secret pact between Hitler and Stalin which carved up Eastern Europe in 1939 - handing Latvia, Estonia and Lithuania to Moscow on a plate.
And the fall of the Nazis in 1945, they say, heralded a second Soviet occupation, which did not end until the collapse of the USSR.
US regional role
President Bush seems to agree. In a letter to the Latvian president this week, Mr Bush noted that "the war marked the Soviet occupation and annexation of Estonia, Latvia and Lithuania and the imposition of communism."
Russia is riled. Senior government officials have denounced the use of the word "occupation". In 1939 Soviet troops, they maintain, were invited into the Baltic countries by local leaders.
Russian President Vladimir Putin says Latvia, Lithuania and Estonia already received an apology from the Soviet parliament back in 1989. He is not planning to issue another.
Mr Bush has promised to share his interpretation of the past with Mr Putin during Victory Day celebrations in Moscow.
More than 50 heads of state are due to attend, including Latvia's president.
But the leaders of Lithuania and Estonia will not be there.
They are boycotting an event which they believe celebrates their country's annexation by the Soviet Union.
Following the 9 May celebrations in Moscow, the US president travels to Georgia - another former Soviet state, with which Moscow today has strained relations.
Like this trip to Latvia, it is a visit which will send another message to the Kremlin - that the US is determined to play a role in a part of the world which used to be in Moscow's sphere of influence.