Syria and Lebanon have formally established diplomatic relations for the first time after years of strained relations and decades during which the regional giant steadfastly refused to recognise its tiny neighbour's sovereignty.
Syria's Walid Muallim kisses Lebanon's Fawzi Sallouk after signing the deal
We present an explanation of 10 stages through which the two purportedly fraternal Arab countries have passed since they both gained independence after WWII.
1- Enduring dispute
Syria and Lebanon never signed up to diplomatic ties after both gained independence in the 1940s, mainly because Syrian nationalists viewed Lebanon as part of an historic Greater Syria and the prevailing Arab nationalist doctrine rejected post-colonial borders dividing Arab states.
Lebanon spawned its own nationalist movements which were determined to preserve the independence of the newly-created, small, mountainous land with its bewildering array of religious minorities.
2 - Civil War saviours
Syrian troops entered Lebanon in 1976 at the request of Lebanese Christian nationalist forces facing defeat in the civil war against a Leftist-Palestinian alliance.
3 - Syria stays on
A force of about 30,000 Syrian troops remained in Lebanon as peacekeepers after the civil war ended in 1990 - as did members of the powerful and feared Syrian intelligence agencies.
4 - Damascus domination
With peace reigning in Lebanon, Damascus showed no sign of wanting to pull its forces out, and it was able to dominate Lebanon - much-weakened by years of civil war - both militarily and politically. Only Lebanese politicians with Syrian backing were able to achieve the highest office.
5 - Visa free-zone
During the post-war period neither the Syrian government nor its clients in Lebanon countenanced the the establishment diplomatic relations between the "brother" countries.
Without embassies or consulates in either capital, Lebanese, Syrians and other Arabs were permitted to cross the border without visas, but foreigners in Lebanon - for example - had to get Syrian visas before they arrived to make the short trip to Damascus.
6 - St Valentine's Day massacre
When former Lebanese PM Rafik Hariri and 20 others were killed on 14 February 2005, many Hariri supporters were convinced that Syrian intelligence officers and their Lebanese cohorts were responsible, after the billionaire politician, formerly a pro-Syrian figure, had joined the anti-Syrian camp. Syria strongly denied responsibility.
7 - US push for democracy
Anti-Syrian feeling had been rising since 2000, when Israel ended its occupation of southern Lebanon, leaving Syrian troops as the only foreign force in Lebanon. The Bush administration became a strong backer of the movement as part of its push for democracy in Arab states.
This is in contrast to the situation in 1990, when Washington had welcomed Syria's help in the war against Iraq and may have turned a blind eye to its role in Lebanon as a result. Significantly, Syria did not help the US in the 2003 invasion of Iraq.
8 - End of occupation
After Hariri's killing, huge anti-Syrian protests in Beirut and massive international pressure led Syria to pull its troops out of Lebanon. This fulfilled UN Security Council Resolution 1559, calling for the withdrawal of foreign forces in Lebanon. A subsequent UN resolution called for Syria to establish diplomatic ties, but it refused.
9 - Lebanese strife
Syria is a strong backer of the powerful Shia Muslim political and military movement in Lebanon, Hezbollah, which has been in the thick of the country's own internal strife. A political unity deal was signed in May giving the opposition led by Hezbollah a new share of power - and Syria's star appeared to rising again in Lebanon.
10 - Current rapprochement
Syria now appears to be on a mission to ingratiate itself again with Western powers. It has embarked on indirect negotiations with Israel mediated by Turkey. France, meanwhile, has brought it to the table with the new unity government in Lebanon, resulting in a rapprochement which includes setting up diplomatic ties, establishing embassies, demarcating borders and investigating the case of missing Lebanese said to have been taken prisoner by Syria.
A cloud on the horizon has been the deployment of about 10,000 Syrian troops on the Lebanese border in the weeks before the historic 15 October embassies agreement. Anti-Syrians in Lebanon fear a new intervention, but Damascus insists it is to counter cross-border smuggling.