Rwandan President Paul Kagame and Uganda's Foreign Minister Sam Kutesa met privately on Wednesday night, as both countries seek an end to political tensions that have paralysed the flow of people and goods across their common border.
The two-hour meeting happened shortly after Mr Kutesa landed in Kigali, well-placed sources confirmed.
The minister delivered a sealed envelope from President Yoweri Museveni to President Kagame but the contents remained a mystery.
Sources said the minister was given a response to deliver to the Ugandan leader.
Mr Kutesa was in Kigali alongside Kirunda Kiveijinja, Uganda's Minister of EAC Affairs, who had a separate mission representing Uganda at the Liberation Day celebrations at Kigali's Amahoro Stadium on Thursday.
Sources told The EastAfrican that the back-and-forth confidential messages between Kagame and Museveni point to efforts by both leaders to resolve political tensions behind closed doors.
The tensions, which surfaced in 2017, culminated in a border crisis, a development that has affected the flow of goods and people between both countries since February.
The Wednesday meeting mirrored a similar event in October last year, when, at the height of strained relations between Rwanda and Uganda, President Museveni sent Mr Kutesa to deliver a letter with undisclosed contents to President Kagame.
Rwanda has, for over three months, blocked its citizens from crossing into Uganda, warning of possible arrest, torture and deportation.
Rwanda has also accused Uganda of supporting rebels and dissidents opposed to Kagame's government, a charge that Museveni denied in a letter addressed to his Rwandan counterpart in March.
Uganda counter-accused Kigali of conducting espionage on its soil, and that its military courts have recently tried citizens of both countries for spying and working for "a foreign government."
Ugandan officials also pointed fingers at Rwanda for instituting new bottlenecks that frustrated transporters of Ugandan exports.
But even amidst these tensions, the neighbours have maintained a level of bilateral partnership, with diplomats meeting and attending summits in either country without restriction.
Last month, two Ugandan senior military officers graduated from Rwanda's Nyakinama Military Academy, in yet another indicator of the fundamentally strong diplomatic ties between the countries.
Lt-Col Charles Aremu and Maj JK Muhindo emerged with Passed Staff Course symbols, signifying successful completion of their tactical training course.
Border communities, however, continue to bear the brunt of the heightened tensions, as the informal trade they depended on for their livelihood has become heavily restricted.
Restriction of informal trade has led to dangerous smuggling activity and illegal border crossings that have on previous occasions led to fatal clashes between smugglers and patrol agents.
Formal trade has also declined. Uganda's exports to Rwanda dropped from $18 million in January 2019 to $14 million the following month, and recorded at a mere $600,000 in April, according to the Bank of Uganda.
Imports from Rwanda, on the other hand, were barely affected by the border troubles, fluctuating between $1.48 million in January 2019 and $0.75 million in February and doubling back to $1.67 million in March.