In its editorial on March 29, The Nation questions the killings taking place in the region bordering China and wonders why the Laotian government remains distressingly silent.

Alarm bells are ringing after a mysterious spate of attacks on foreigners in northern Laos.

With locals also suffering in the months-long outbreak of assaults and robberies, the government needs to intervene in what has become a threat to security in the region that borders China.

In the latest assault, on Wednesday, unidentified gunmen opened fire on a pickup truck, killing its driver, and a passenger bus that was following, leaving six Chinese passengers wounded.

They were travelling to Vientiane from Kunming in Yunnan province.

Similar incidents took place on Jan 24 and March 1.

In the latter, a Chinese worker was killed and three others injured in an attack by similarly unidentified assailants in Luang Prabang's Phoukhoun district.

An hour later another attack took place in the same district when a bus travelling from Vientiane to Phongsaly province was shot up and three Lao were hurt.

At least two more Lao riding in an accompanying pickup were injured as well.

On January 24 two Chinese were killed and another injured in a bombing in northern Xaysomboun province.

One of them was employed at a mining company in Yunnan. No one has claimed responsibility in any of these incidents.

The United States Embassy in Vientiane issued a travel warning on March 8 and barred its officials from utilising Highway 13 between Kasi near the capital to Luang Prabang province.

It cited "the unpredictable nature of the violence and the lack of official information regarding possible motives or a Lao government response".

The government has failed to respond to the attacks even after Beijing called on its authorities to investigate the violence.

There has been no indication how or even whether the government plans to deal with the situation.

In the absence of any type of explanation from the authorities, speculation has been rife, with blame for the attacks attributed to everyone from common robbers to anti-government militants.

In terms of security, Luang Prabang's Phoukhone district, Xaysomboun province and much of Highway 13, especially between the tourism destinations of Vang Viang and Kasi close to Vientiane, have been vulnerable zones for some time.

Though fiercely suppressed and short of public support, an anti-government movement has remained sporadically active ever since communists swept to power in 1975, but its members keep a low profile and militancy action has been largely phased out for more than a decade.

The government no longer considers it a likely threat, although it monitors its activities carefully, even recruiting the help of neighbouring countries such as Thailand.

Geopolitical changes in recent years might have sparked fresh activity.

If Chinese travellers are being targeted in these latest attacks, it could stem from China's substantial political and economic influence on Laos.

At the same time, Laos has drawn closer to the US, which could have reopened old wounds and prodded militants to try and jeopardise that tie.

It's also possible that the attacks are intended to warn both of the superpowers, the US and China, that Laos is not as secure as their investors might hope.

What is less likely is that domestic political issues are fuelling the attacks, since the country is in transition, with a new leadership moving into position.

The first attack in January coincided with a congress of the ruling People's Revolutionary Party, at which voting was held to replace most of the old guard.

The latest attack took place only a week after the country's general election.

Adding to the country's discomfiture is the fact that it is this year in the chair for Asean.

As such it will be hosting international meetings, albeit not in its troubled north.

Regardless of the real motivation for the attacks there, the government is obliged to shoulder its responsibilities and ensure everyone's safety.

Failing to offer any accounting for the attacks or a plan of action to curb them is instead irresponsible. Silence is helpful to no one.

The Nation is a member of The Straits Times media partner Asia News Network, an alliance of 22 Asian newspapers.