Rwanda says it will not hesitate to fight the United Nations Force Intervention Brigade (FIB) in the Democratic Republic of Congo (DRC) if there is evidence that it formed part of the Congolese soldiers accused of shelling Rwanda.
If that happens, South African soldiers and those deployed with them under UN auspices might just find themselves trapped in the middle of a regional conflict.
Rwanda's ambassador to South Africa, Vincent Karega, told the Mail & Guardian in an interview this week that, although the country did not seek to engage in violent confrontation, it could not but see the shelling that killed a Rwandan woman and wounded her baby as an act of provocation.
UN forces have been fighting alongside the Congolese FARDC (a French acronym for the DRC's national army) to push back the well-armed M23 rebels who were threatening to take the town of Goma in North Kivu province.
Rwanda is prepared to protect its citizens, even if it means facing off against soldiers from countries "friendly" to it, he said.
Tensions grew last week, as Rwanda embarked on a military build-up near its border with the DRC after shells fell in the Rwandan town of Rubavu.
Rwanda believes the shelling is a way of drawing the country into the DRC conflict with M23, whereas the Congolese government claims that M23 rebels intentionally shelled Rwanda in an attempt to draw the country into the conflict to support the movement.
At the time, Rwanda's foreign affairs minister, Louise Mushikiwabo, said her country could no longer tolerate the provocation.
"We have the capacity to determine who fired at us and will not hesitate to defend our territory," Mushikiwabo said.
This week, Karega said Rwanda had no reason to suspect UN forces of taking part in shelling the country 34 times in the 10 days of fighting against M23 rebels, but cautioned the brigade against "violating their own mandate, which is not to attack Rwanda, but to stabilise the DRC".
"We are not looking for war. If it was a tit-for-tat, we'd have gone into it from the first shelling," he said.
"But in a situation where people continue to be stubborn and we know a particular point in Congo that is doing this shelling, the troops that will be there and the machines that will be shelling Rwanda, we can shoot them down or push them to a certain distance where we are sure they cannot play that."
Karega said his country understood that the UN brigade had no choice but to support FARDC to protect Goma and surrounding areas when fighting M23 until last week.
"But while doing that, they should be careful to remain neutral and avoid creating new tension."
M23 initiated a ceasefire last Friday, saying it wanted to give peace talks a chance. The talks are now taking place in Uganda's capital, Kampala. Rwanda maintains that it is committed to peace in the DRC and the agreements that the two countries have signed to avoid conflict. Karega, however, said UN forces should play their role effectively to ensure that peace held.
"We trust the South Africans, Tanzanians and Malawians who are there to help the Congolese are also going to assist them with discipline and to focus on the target," he said. "They're not going to let [the Congolese army] play other games that are going to complicate the conflict."
However, Karega warned: "In a case where they [the UN forces and FARDC] happen to be together and own the action of shelling Rwanda together, then they would have violated lives in our country. Why should we fear for their lives?
"As much as we don't want to be in trouble with friendly countries that we partner with, in a situation where they find themselves in a group fighting us, we don't have a choice."
Rwanda has often been accused of supporting M23 rebels against the DRC government and relations between the two countries are sensitive.
On the other hand, Rwanda has accused the DRC of accommodating Democratic Forces for the Liberation of Rwanda (FDLR) rebels, who have among them a large number of original members of the Interahamwe that carried out the 1994 genocide.
Karega said, for the DRC government to work with the FDLR was "a big slap in the face", considering that Rwanda had helped President Joseph Kabila's father, Laurent Kabila, to topple dictator Mobutu Sese Seko.
On funding the M23, Karega said: "Why should we fund a rebel movement? We cannot sustain a war that has been there for 20 years and serves no purpose for us."
If the UN brigade forces did not take part in shelling Rwanda, the least they could do was to help to identify the Congolese soldiers who did, Karega said.