Abramov (2000), Kurose et al. (2000), and Graphodatsky et al. (1976) supported species-level separation of itatsi from Siberian Weasel Mustela sibirica. Mustela lutreolina of Java and Sumatra is also sometimes considered part of M. sibirica (e.g., Corbet 1978). Both are here considered distinct. The taxonomic status of the Central Asian and Himalayan populations of M. sibirica is uncertain.

Siberian Weasel is listed as Least Concern in view of its wide distribution, evident large population over much of it range, and because it is unlikely to be declining at the rate required to qualify for listing even for Near Threatened.

Siberian Weasel is recorded widely across the East Palaearctic, west in Russia to Kirov Province, Tatarstan and the western Ural Mountains, and east to the Pacific coast, the islands of Taiwan (province of China) and Jeju (Republic of Korea); while it occurs south to the Himalayas (from Pakistan and Kashmir east to northern Myanmar), a large part of arid east-central Asia (north and west China, and southern Mongolia), is apparently not occupied (Pocock 1941, Wang 2003, Abe 2005, Wozencraft 2005). The distribution in South-east Asia is poorly known (A. Abramov pers. comm. 2006) and, outside Myanmar, where it is known only from the far north, is probably disjunct from the main Palaearctic/Himalayan/Chinese range. Although the species is fairly widespread in southern China almost to the Viet Namese border (Lau et al. 2010), there are no record from Viet Nam (Roberton 2007). Lekagul and McNeely (1977) included the species in the mammal fauna of Thailand without giving specific records; it was apparently recorded subsequently in two national parks (B. Kanchanasaka pers. comm. 2006), but Chutipong et al. (2014), in an exhaustive collation of recent small carnivore records from Thailand, found no recent records at all. There are unconfirmed sight records from 1-2 location in Lao PDR, both in the centre: Nakai-Nam Theun National Biodiversity Conservation Area (Duckworth 1997) and Phou Hinpoun National Biodiversity Conservation Area (Robinson and Webber 1998). The pattern of natural occurrence in central and northern China is confounded by widespread release of the species, although release is not known in the south (Bosco P. L. Chan per. comm. 2014). In Japan, it has been introduced to Honshu, Shikoku, and Kyushu Islands (Abe 2005, Sasaki et al. 2014). A bird-watcher observed a healthy-looking individual at large in an agricultural landscape of Hong Kong a few years before 2014; this animal must have been a release or escape (Bosco P.L. Chan pers. comm. 2014).

Altitudinal distribution varies greatly across its range. In the north, such as Korea, it occurs right down to sea-level (J. W. Duckworth pers. comm. 2014). In the Himalayas, it seems to be strictly montane, with, for example, records from Myanmar coming from the range of 1,070-4,120 m (Than Zaw et al. 2008), in north-western Yunnan province, China, along the upper Mekong, up to at least 3,500 m (Bosco P.L. Chan pers. comm. 2014), in Khangchendzonga Biosphere Reserve, Sikkim, India, over 3,000-4,000 m (Sathyakumar et al. 2011), in Nepal from 2,600 to 3,200 m (Y. Ghimirey pers. comm. 2014, V. Dinets pers. comm. 2015), in Bhutan, from 1,500 to 4,800 m (Thinley 2004), and in India and neighbouring areas, 5,000-16,000 feet (1,500-4,875 m). The altitudinal usage of the Thai/Lao populations is poorly known, with Lao records at 500 and 1,000 m, much lower than elsewhere in its southern range.

The species is widespread and abundant in southern Siberia, northern Mongolia and China. It is also common in north-central Korea, where few other mammals other than rats and squirrels are currently easily seen (J. W. Duckworth pers. comm. 2006). In its Chinese range, outside the southern region, it is probably the most readily-seen carnivore because of its diurnal and bold habits, as well as its attraction to village rodents (Bosco P.L. Chan pers. comm. 2014). Recent published records from the Himalaya are rather few (e.g., Nepal; Ghimirey et al. 2014), but the extent to which this indicates genuine scarcity of low levels of relevant survey effort is not clear: it was common around Lukla, Nepal, in 1997 (V. Dinets pers. comm. 2015). High fluctuations of population density are known for the Siberian populations (Heptner et al. 1967).

Siberian Weasel is found in primary and secondary deciduous, coniferous and mixed forests, as well as open areas with small patches of forest and forest steppe. It is commonly found living and breeding in farmland landscapes in rural China, apparently attracted by the high rodent density. In big cities in central and northern China, such as Beijing, it is regularly found breeding in built-up areas; how much its pattern of occurrence there is confounded by widespread release of the species for rat-control is not sure (Bosco P.L. Chan pers. comm. 2014). It is also found along river valleys, and occasionally above the tree line in the mountains (V. Dinets pers. comm. 2015). It feeds on small mammals, such as voles, squirrels, mice, and pikas, on amphibians, fish, and carrion, and, when they are seasonally available, on pine Pinus nuts. Camera-trap and direct observation suggest the species is largely diurnal, although it has been camera-trapped and sighted directly active at night (Bosco P.L. Chan pers. comm. 2014, V. Dinets pers. comm. 2015).

There are no major threats known to Siberian Weasel. Heavy hunting levels in China possibly cause localise declines (Gao and Sun 2005, Lau et al. 2010). Competition for resources with Sable Martes zibellina and natural wildfires have been suggested possibly to constitute minor threats. In Arunachal Pradesh, India, one road-kill and many skins were recorded in recent years. It is snared, or killed by various other means, when it comes to habitations for stealing poultry (A. U. Choudhury pers. comm. 2014)

It is legally hunted in Russia for its fur (A.V. Abramov pers. comm. 2006). Russian painters particularly value paintbrushes made of its tail hair (V. Dinets pers. comm. 2015). "Unfortunately, the small forest carnivores are not well protected by either local forest managers or the residents living in the forest areas in China, though most of them are listed as protected animals by the national or local governments. Weasels and badgers are largely hunted for their hides and meat" (Gao and Sun 2005). Lau et al. (2010) also remarked on the widespread, intensive and potentially unsustainable hunting for skins in southern China. However, in some areas, hunting levels are low at present, reflecting the low commercial value of skins.

Siberian Weasel is listed on CITES Appendix III (India). It is protected in Tibet (Li et al. 2000) and Thailand (Chutipong et al. 2014). It is on the China Red List as Near Threatened, because it was assessed as nearly meeting the threshold of decline rate for Vulnerable A2cd. It occurs in many protected areas in both its Himalayan and its Palaearctic range. It is unclear if present harvest levels are sustainable in the long term; there is no population monitoring. The current abundance in various parts of its range in China and Russia indicate that there is unlikely to be an urgent need for more scientifically based management.