FREDERICK, Md. — The Washington-Moscow Hot Line, used by US and Russian leaders for frank discussions about crises including the 1967 Six-Day War and the Soviet Union’s 1979 invasion of Afghanistan, marked its 50th birthday Thursday with the nations still grappling with competing interests in regional conflicts.
The direct connection, established during the Cold War by a relatively simple telegraph system, now includes telephone and e-mail capabilities and will soon add video, said White House National Security Council spokeswoman Laura Lucas.
‘‘The president continues to value the direct communications link between Washington and Moscow,’’ Lucas wrote in an e-mail response to questions about the hot line.
The next crisis could be around the corner, said Roald Sagdeev, a former director of the Soviet space program, who spoke at an anniversary celebration at Fort Detrick, where the US Army maintains a satellite link for the hot line.
‘‘It’s very important to make sure we can keep this, especially at the time of what’s happening in Syria,’’ Sagdeev, a University of Maryland physics professor, said before the event.
Despite myth and movie lore, the president does not use a red phone to talk with his Russian counterpart. In fact, the connection established in 1963 was for written communications only. Voice was added two decades later as the system evolved from an undersea telegraph cable to today’s satellite and fiber-optics system.
‘‘The system is very robust, as you might imagine,’’ said Craig Bouma, civilian executive officer at Detrick Earth Station, who manages the twin satellite dishes and 16 civilian Army employees — eight technicians and eight linguists. They work around the clock to ensure the system is operating correctly. The station also handles secure communication for the Pentagon and State Department, including a link the nations use to alert each other to missile tests.
In June, the United States and Russia signed a pact to add a direct communications link to prevent the inadvertent escalation of misunderstood cybersecurity incidents.
Until February, the Washington-Moscow link was operated by Honeywell under a five-year, $8.4 million contract.
Bouma said workers at Detrick interact daily with their Russian counterparts in written exchanges that sometimes reveal cultural differences.
‘‘The Russians express themselves in very flowery text: ‘Dear esteemed colleague, greetings.’ ’’ Bouma said. ‘‘My linguist says that’s very common in the Russian culture.’’
The link was set up after the 1962 Cuban missile crisis to prevent accidental nuclear war. Known at the Pentagon as MOLINK, for Moscow Link, it went live Aug. 30, 1963, with this US-generated message: ‘‘The quick brown fox jumped over the lazy dog’s back 1234567890.’’
The hot line’s first use in a crisis came during the six-day Arab-Israeli war in 1967, said Michael Bohn, a former Situation Room director and author. He said Soviet Premier Alexei Kosygin sent a message to President Lyndon B. Johnson at 7:47 a.m. on June 5, 1967, after Israel preemptively attacked Egypt, Syria, and Jordan. The message expressed Russia’s hope the US government would ‘‘exert appropriate influence on the Government of Israel particularly since you have all opportunities of doing so.’’
Bohn said the leaders exchanged 19 messages during the Six-Day War. He also documented use of the link by presidents Richard M. Nixon, Jimmy Carter, and Ronald Reagan.
Starting with President George H.W. Bush in the early 1990s, telephone calls replaced written messages as the preferred mode of communication, Bohn said. He said that when the link was created, written messages were seen as safer.
‘‘In a tough situation, you have to be careful what you say. The process of sitting down and writing it out clears your head a little bit and makes you slow down a little bit and think twice — that’s what people have told me,’’ Bohn said.
President Obama and President Vladimir Putin spoke in March. Obama phoned to welcome Russian cooperation on confronting Iran’s nuclear ambitions.