At least two mortar shells fired by Myanmar into Bangladesh territory on Sept 3 were illegal under international law.
The event occurred five days after Bangladeshi officials summoned Myanmar's ambassador in Dhaka and protested over Myanmar's firing of two deadly shells at the same location on Aug 28.
According to the police investigation centre at Ghumdum in the hill area of Bandarban, at least two fighter jets flew over the Bangladesh border firing at least eight rounds, while two military helicopters fired more than 30 shells.
Bangladesh has reiterated its "deep concern" over Myanmar's violation of an air border agreement.
In addition to suppressing internal rebels (the Arakan Army), the presence of the Myanmar army on the border is again raising fears of Rohingya's infiltration into Bangladesh. There have been allegations of inaction to deport the remaining Rohingya staying in the country through manoeuvring. In this situation, residents have announced new steps to prevent intrusions.
For the past few days, there has been ongoing conflict in Rakhine State, an area bordering Bangladesh and India in Myanmar, which is affecting neighbouring countries as well. The residents of Ghumdum, and the Tambru border areas of Bandarban are panicking. Some people took refuge in India.
As the Myanmar army is fighting the Arakan Army in Rakhine, the Myanmar army has started a major military operation against the rebel groups in Kayah, Kain and Chin states. The military forces of that country are also using helicopters and warplanes in this war.
The military junta wants to hold elections in Myanmar in August 2023. Before that they want to establish their complete control over Rakhine and other states.
Rakhine State is particularly important to them, as the state shares a border with Bangladesh and India. Where conflict is taking place, that too is just across the border in Bangladesh.
As a result, Bangladeshi residents of the border area are terrified of the conflict there. Four and a half thousand Rohingya have been living on the Tambru border line in Naikshatchari for the past few years, where this violence is occurring. Due to the violence, there are fears they will move into Bangladesh.
It has been alleged that there is a plot to move the remaining Rohingya in Myanmar to Bangladesh.
As of August 2017, the Myanmar Army has been flying warplanes and helicopters along the border of Bangladesh. Mortar shells and bullets have been fired into Bangladesh. Locals complain that this is Myanmar's strategy to cause the infiltration of Rohingya into the country.
The two shells fired on Aug 28 landed half a kilometre inside the Tambru border but did not do any damage, in contrast to the two shells fired on Sept 3 at Tambru on the Ghumdum border, which burst about 120 metres inside Bangladeshi territory.
We express our outrage at Myanmar's flagrant disregard for international law, demonstrated by its twice-weekly firing of deadly shells into Bangladesh despite previous complaints following the initial breach on Aug 28.
Usually, when an operation is carried out near the border, a warning is given if there is a relationship between the two states. But no such information was given to Bangladesh. It is a violation of international norms not to inform Bangladesh before conducting operations against Arakan.
But this is not Myanmar's first offence against international law. In September 2017, shortly after launching a genocide against the Rohingya and driving a sizeable number of them out of its Rakhine state and into Bangladesh, it repeatedly violated Bangladesh's airspace for a week.
Additionally, it continued to instil fear in Rakhine State so that none of the 1.2 million Rohingya who are currently seeking refuge in Bangladesh would agree to go back to their home country.
Such activities pose a serious threat to the safety and undermines a sustainable process of Rohingya repatriation.
It appears that Bangladesh, which has about 165 million people, or about three times as many as Myanmar, is the target of such violations of international law by the military-run Myanmar, which has a poor reputation among other states worldwide.
This could be because Bangladesh has an international reputation in terms of politics and strategy as a peaceful country.
Yet Myanmar must understand that Bangladesh is also a militarily capable country. If Myanmar continues to pursue an offensive strategy, Bangladesh can take a defensive approach along the border. This could destabilise the whole region.
Although Bangladeshi officials claim to be closely monitoring events, the incident is sufficient to raise questions about Bangladesh's security and territorial integrity.
On Sunday, Bangladesh reaffirmed its "grave concern" about recent incidents including mortar shelling from Myanmar, indiscriminate aerial firing in the border regions, and violations of airspace.
The Bangladeshi foreign ministry protested against the recent incidents along the Bangladesh-Myanmar border and summoned Myanmar's Ambassador to Bangladesh Aung Kyaw Moe.
The ministry had called the envoy three times in a little over a week to express its deep-rooted concerns.
The circumstances call for Bangladeshi authorities to make stern diplomatic objections over Myanmar's behaviour and to take the necessary steps to prevent similar incidents from happening in the future.
Arpita Hazarika is a researcher at Gauhati University, in Assam, India. She has written about refugee affairs, political economy and foreign policies in the Asia-Pacific region.