Despite differences that spurred civil war and cost tens of thousands of lives, the Tamils and the Sinhalese from Sri Lanka have at least one thing in common: a love of tea.

But some Tamil Americans say they are cautious when they go to Dupont Circle’s Teaism because their archenemies — the ethnically Sinhalese Sri Lankan Embassy staff — might also be in there sipping Ceylon green from the old country.

“We would prefer not to have any big, public arguments right now,” said Vimala Ranjithan, a Tamil American physician who lives in Cumberland, Md.

The quarter-century-long civil war between the separatist Tamil Tiger rebel group and the largely Sinhalese Sri Lankan government officially ended in 2009. But halfway around the world, the two groups continue to come to verbal blows, enduring awkward run-ins at seemingly neutral locales.

“They can target you,” said Ranjithan, who wears a disguise with sunglasses when she goes to a protest against what she considers the Sri Lankan government’s discrimination against Tamils. She echoes a fear that many Tamil Americans voiced in interviews: that their critical words in Washington could result in the arrest or harassment of relatives back home.

Sri Lankan Americans aren’t the only Washingtonians who find themselves avoiding their foes on the streets of downtown Washington. The de facto capital of the world is a high-profile stage for expatriate rivals who, on their own turf, might be engaged in guerrilla warfare. Instead, they avoid one another at suburban strip malls, skirt confrontation at embassy cultural events or duck punches at political meet-ups when fights break out over conflicts that are unfolding thousands of miles away.

In Washington’s international circles, the acrimonious relations between long-standing enemies such as India and Pakistan, Palestinians and Israel, and Tibet and China are well-known, not least because they have some of the most organized and well-funded advocacy groups in the country. But the alleged high-profile Iranian plot to assassinate the Saudi ambassador to Washington while he dined at his favorite restaurant was just one example of the subterfuge and animosities still smoldering just under the city’s surface.

What happens in D.C. . . .

From his offices on Capitol Hill, Fred Turner’s job is to focus on how these conflicts unfold on the ground in Washington.

“The truth is that Washington still plays an outsize role on the world stage. And what happens in Washington gets reported back to Budapest, Bakou or Berlin. Of course, that amplifies what happens here,” said Turner, deputy chief of staff for the independent U.S. Helsinki Commission, a government agency whose mission is to monitor the frozen conflicts, human rights violations and security breaches in 56 nations in Europe and Central Asia.

For example, the Turkish Republic of Northern Cyprus has a K Street office in Washington. Those who live there consider themselves an independent country, even though the U.S. government does not recognize them as one. It’s known to the rest of the region as occupied Northern Cyprus, separate since Turkish troops invaded in 1974.

When the Helsinki Commission recently held a hearing on the destruction of religious property “in Cyprus,” representatives of the Turkish Embassy got upset and asked that the hearing’s name be changed, Turner said. The commission invited the Government of Turkey to participate, but it declined.

“We’re looking at these issues here every single day,” Turner said. “Even a simple movie screening has instigated diplomatic fireworks.”

Frontline: Washington

One such fireworks display took place recently, when the Sri Lankan Embassy hosted a screening of the government-produced film “Lies Agreed Upon” during a briefing in Congress on rebuilding the country. The documentary is a rebuttal of reporting by Britain’s Channel 4 News on alleged war crimes perpetrated by the Sri Lankan government.

Tamil American groups in the area quickly voiced objections. Among them was Grace Williams, a Tamil American who came to the United States in 1978. During an interview, she lugs out an encyclopedia-size photography book with the blunt title “Genocide in Sri Lanka.” It includes hundreds of pictures of anti-Tamil riots, chronicles the disappearances of Tamil men and lists names of allegedly assassinated Tamil political party leaders.

This isn’t the first time that Williams, 54, a Bowie resident and retired health-care advocate for special-needs children, has been drawn back into the 26-year conflict. After she took part in a summer memorial ceremony outside the Capitol honoring the Tamil dead, someone speaking in the Sinhalese language left a threatening message on her voice mail, she said.

“I called both my senators,” said Williams, who is also assistant secretary of the U.S. Tamil Political Action Council, a Tamil activist group. “They shouldn’t be doing this in America. But Washington is where these fights are often fought — Washington is another frontline of these conflicts.”

Sri Lankan Ambassador Jaliya Wickramasuriya said in an interview that Tamil American groups are usually fronts for the Tamil Tigers, a rebel movement long on the U.S. list of terrorist organizations. In 2006, the FBI investigated the Tamil Rehabilitation Organization, which has a branch in Cumberland, for allegedly financing the Tamil Tigers through a tsunami relief fund. The U.S. Department of the Treasury shut the charity down when the allegations were substantiated. (Tamil Americans say the accusations were unfair and that funds were indeed used to help victims of the tsunami.)

“We work with the U.S. and FBI to try and figure out who is connected and who is not,” said the ambassador, who added that he thinks most Tamil Americans just want to help rebuild the country. “The diaspora is very active in Washington, and it keeps these issues alive, even when people back home have moved on.”

Century-old hostilities

Although some of the tensions between international antagonists are high-level and unfold in official channels, they also manifest quietly, as chilly silences or suspicious glances between individuals from warring nations.

On a recent evening, Ali Abudul Latif, a cabdriver from northern Sudan, was surprised to find that the new nation of South Sudan, with which his country spent years at war, was holding a conference in Washington. Salva Kiir, the new country’s president, was even speaking at a downtown hotel.

Latif fled Sudan because he was a teacher and didn’t want to fight. But when he found himself picking up fares at the very hotel where Kiir, once South Sudan’s top rebel commander, was being feted, it wasn’t the taste of home he was looking for in Washington.

“I’m still wishing we could be one nation,” he said as he began to drive. “Washington is far away from home, yet home to so many enemies.”

Time has proved as ineffectual as distance in quelling such disputes.

In April, members of Washington’s Armenian community held a silent vigil at the Turkish Embassy to commemorate the Armenian genocide of 1915 to 1923.

On the other side of the street, vigil participants say, those sympathetic to the Turkish government, which does not acknowledge that the events of the era constituted genocide, waved baseball bats and sang and danced in the streets. The police were called.

Turkish people who attended the counter-rally but asked not to be named said they were simply mocking the idea of protesting such an old issue.

“It’s totally rude,” said Aram Hamparian, who lives in Bethesda and is executive director of the Washington-based Armenian National Committee of America. “Armenian Americans were deeply hurt to see that allies of Ankara were not simply denying the Armenian genocide but actually celebrating the destruction of an entire nation.”

Violence erupts

Sometimes verbal confrontations can turn violent. Last year, a brawl erupted at Howard University, which was hosting an outreach forum for the Ethiopian government. A team of delegates sent by Prime Minister Meles Zenawi was on hand to persuade representatives of the economically successful Washington diaspora here to support his five-year development plan. (Washington is home to the world’s largest Ethiopian expatriate community, with more than 100,000 people, and sends millions of dollars back home.)

Part of the government’s agenda at the Howard event was to raise money from Ethiopian American business owners for an expensive dam project.

That proved a tough sell. Many Ethiopian Americans accuse their home country’s autocratic government of widespread corruption and are active in opposition parties.

Some of the business leaders present were holding up signs that read, “No diaspora money for despots with Swiss bank accounts.” Suddenly, a punch was thrown from the government side, witnesses say.

“It was so shocking, because it was happening on a Washington campus,” said radio host Abebe Belew, who covered the event and is known as “Ethiopia’s al-Jazeera” for his hard-charging political broadcasts for an Ethiopian diaspora show called “Addis Dimts” (the Ahmaric word for voice) on Centreville-based WTNT.

“The police came out. The university had to cancel the whole meeting,” said Belew, who lives in Silver Spring. “It just shows you how important these meetings in Washington can be.”

Seeking a voice

Perversely, many of these combatants are drawn to Washington for the same reason: Its proximity to the U.S. government makes it an ideal base for lobbying efforts. “Our arsenal is not weapons,” said Nick Larigakis, president of the American Hellenic Institute, which promotes U.S. relations with Greece and Cyprus and is often at odds with Turkey’s goals. “It’s having a voice in Washington where we can use the rule of law to provide credibility to our arguments.”

Sometimes there are victories.

Turkey was allegedly denying religious freedom to Ecumenical Patriarch Bartholomew, who is head of the Greek Orthodox minority in Istanbul but also the spiritual leader of all Orthodox Christians.

But steady lobbying by the Greek community here to recent administrations helped pressure Turkey to improve religious freedoms there, said Andy Manatos, who, along with his father, Mike Manatos, runs one of Washington’s most powerful lobbyist firms.

“Washington is far and away the most effective place if you want your issues addressed,” said Manatos, who focuses on international issues and also does pro-bono work for the Greek Orthodox Church. “If you can convince the most powerful people in the world of the truth of your cause, I know of no place in the world better for advocating your issue.”

Protesting, but warily

Sometimes there are further divisions.

On Branch Avenue in Prince George’s Country, an Ethiopian church recently opened soon after an Eritrean one — religious outposts of longtime rivals and two of the poorest nations on Earth.

“How can you make politics when you are praying to God?” asked Imru Zelleke, a retired Ethiopian ambassador to Germany who lives in Arlington County and heads a civic group that’s trying to bring immigrants from the countries together.

In his Pentagon City apartment, amid books about Africa’s tribal divisions, Zelleke shook his head. “It’s the same religion. It’s just absurd and a waste of money,” he said. “We could be sending that money to help our countries. I thought we got over this when we came to Washington.”

But on a cold December day, on the cobblestone streets of Old Town Alexandria, the Tamil American community said their fight was far from over.

They were holding up signs that read, “Victoria’s Dirty Little Secret” and “Big GAP in ethics” in front of Banana Republic and the Gap, warning shoppers to check labels, lest they buy clothing made in Sri Lanka, where they say human rights violations are continuing and Tamils are being forced off their land by the government.

“We need jobs in America, not in a country accused of war crimes,” they chanted.

The wind was piercing, but under a banner that read “Stop Tamil Genocide” they had their cause to keep them warm. And Williams and the other protesters were there, dressed in oversize hats and sunglasses — just in case the enemy was watching.