Investors are concerned that negotiations and non-violent actions will not encourage North Korea to stop its nuclear program. In fact, it may only encourage North Korea to use more provocative actions (as we saw a week ago when it tested a ballistic missile that went above Japanese territory).

Although there are no signs yet of the preparation of a military operation, US President Donald Trump said he may implement more economic sanctions to punish North Korea. On his twitter account Trump suggested to cut off trade with any nation that does business with North Korea, a move that would affect China. It is assumed North Korea is working on a hydrogen bomb - loaded onto an intercontinental ballistic missile - that is capable of reaching the United States.

Amid heightened concerns, safe haven assets - such as gold, Japan's yen, the Swiss franc, and sovereign bonds - are in demand. Japan's Nikkei index is leading losses in Asia so far on Monday due to the strengthening yen (which makes Japan's export-oriented stocks less attractive). South Korean defense stocks, on the other hand, surged (although, overall, South Korean stocks are in the red).

By 11:25 am local Jakarta time Indonesia's benchmark Jakarta Composite Index was down 0.49 percent to 5,835.35 points, while the rupiah had depreciated 0.14 percent to IDR 13,337 per US dollar. Markets in Malaysia and Vietnam are closed for public holidays.

Meanwhile, a relatively weak August 2017 US jobs report reinforced investors' expectations that the Federal Reserve will not raise rates too soon. Non-farm payroll employment rose by a modest 156,000 jobs in August, while analysts expected a 180,000 jobs increase.