NEW DELHI — India's army attacked separatist rebels just over the border with Myanmar on Tuesday, a rare cross-border strike that the government said showed its resolve to fight terrorism beyond the country's borders. The raid on two groups of militants was carried out in retaliation for the killing of 20 soldiers in an ambush in the northeastern state of Manipur last week, the heaviest losses for security forces in Manipur in two decades. The mountainous northeast which borders China, Bhutan, Bangladesh and Myanmar, is home to dozens of insurgent groups fighting for autonomy or secession from India. For decades, soldiers have been deployed in the region but they are not known to have crossed borders even though the military says rebels have sanctuaries in Myanmar, Bangladesh and Bhutan. The army said in a statement it had received intelligence that guerrillas were plotting more ambushes after last week's attack on a convoy. It said soldiers inflicted “significant casualties” but gave not details. The army did not say soldiers had crossed the border but the government did. Junior Minister for Information and Broadcasting Rajyavardhan Singh Rathore said the government had taken the bold step to strike at militant camps and he congratulated Prime Minister Narendra Modi for doing so. He also told NDTV it was a signal to neighbors that India will not tolerate militant attacks from across its borders. “It is undoubtedly a message to all nations that harbor any intentions — be it the west or the specific country we went into right now. Even if there are groups within countries that harbor terror intentions, we will choose the time and the place of hitting them.” India's top security concern is Pakistan which it has long blamed for stoking a revolt in Muslim-majority Kashmir as well as giving material support to Pakistan-based militants for attacks in other parts of India, including a bloody 2008 assault in the city of Mumbai. Pakistan denies the accusation and says it is fighting militants. Modi's Bharatiya Janata Party has long advocated a tough stance toward Pakistan including the option of hot pursuit of militants. Since coming to power Modi has sought to ease tension but ties remain fragile. The Indian army said it was in communication with Myanmar regarding its operations against guerrillas, adding there was a history of cooperation. Former army chief General V.P. Malik said the Myanmar army was thinly deployed where the latest operations took place. “I think they would have sounded out the Myanmar authorities before going in,” he said. — Reuters