Was he not invited or did he elect not to attend (and despatched National Development Minister Lawrence Wong instead)? The former seems the more plausible account. Either way, the development can only be described as doomy.
The summit, attended by 28 heads of government, is Beijing's way of announcing its intention of breaking out from under the United State's world domination, at least in the sphere of trade and commerce.
So why is our PM left out of the summit? The short answer is that China is peeved that Singapore remains an integral part of the US' security network in Asia, a network Beijing sees as designed to contain its growth.
At the regularly organised China-Singapore forum held just days before the summit, China continued its diatribe that we had spearheaded the effort last year to get Asean countries to sign a statement supporting an international tribunal's ruling against Beijing's territorial claims over the South China Sea.
Our representative Prof Tommy Koh demurred, explaining, unconvincingly perhaps, that Singapore was not aligned with the US.
Unconvincing because in 2016, PM Lee was feted at a high profile visit to Washington DC during which then President Barack Obama stated plainly that Singapore "is an anchor of (the US') presence in the region". Mr Obama was speaking more than metaphorically because we are hosts to the US navy's warships.
This is not lost on China who pointed out at the forum that the Changi Naval Base allows the US to deploy military vessels and aircraft meant for "close-in reconnaissance in China's South China Sea" even though we claim not to be aligned with the Americans.
Mr Lee himself has provided the Chinese ample rope with which to hang us: He was the leading proponent of the Trans-Pacific Partnership trade deal that did not include China, lectured that China was no longer the Middle Kingdom, and even poked fun at our giant neighbour with what can only be described as humour unbefitting a head of government – and in front of an American audience to boot.
These developments have caused China to view us with suspicion and animosity. Little surprise then that Beijing is doing all that is within its means – which are considerable – to bypass Singapore as the key node in international trade. It endeavours to control its own shipping interests rather than be dependent on a US satellite-port.
Here are are five ways Beijing is doing this:
1. Melaka Gateway. China is working with Malaysia to develop a $14-billion harbour in Melaka (Malacca) which aims to rival our port. The Gateway in the Malacca Strait – which moves 80 per cent of China's energy needs and sees 100,000 vessels, most of them Chinese, ply its waters – will be ready by 2019.
2. East Coast Railway Line (ECRL). Plans for a railway line spanning the width of peninsula Malaysia thereby linking the Malacca Strait to the South China Sea are underway. The project will again stop cargo from transiting through Singapore. “In 10 years or so, Malaysia can say bye-bye to Singapore," said a seasoned port and logistics consultant who has worked in Singapore, Malaysia and China.
3. New Silk Road. The revival of this ancient route linking China and Europe will increase direct trade between the two giant markets, again, by-passing Singapore.
4. Arctic Route. As the polar caps melt due to global warming, sea routes open up. China has signaled that its ships will take this northern passage to cut travel times between the Atlantic and Pacific oceans.
5. Kra Canal. The long-running idea to cut a channel through the Isthmus of Kra, a project which China is interested to undertake, will significantly cut shipping time between the East and West.
Of course, none of these projects presuppose success. They face a myriad of problems in execution, including economic and geopolitical factors which could conspire against Beijing's best-laid plans.
For instance, it seems counter-productive to build the ECRL in Malaysia and then cut the Kra Canal in Thailand. The New Silk Road could be constrained by lack of financial resources. Or political change across the Causeway could disrupt plans for the Melaka Gateway.
But even if one these initiatives partially succeed, our status as the aorta of international trade will be critically jeopardised. Imagine the havoc that this will wreak on our economy.
This is why the PAP's insistence of remaining in US' political orbit is so perilously ossified. No one is suggesting that we genuflect to Beijing, but our foreign policy in as far as the US-China alignment is concerned needs urgent re-calibration – that is, if it's not already too late to do so.
On this front, the current set of ministers seem bereft of ideas in how to deal with the fast-changing geopolitical circumstance.
What we need to do to avoid – and if it is inevitable, overcome – these monumental challenges that lie ahead for our nation is to require the attention, energy and passion of our people – all of our people.
We need a genuine national debate where all cards are on the table: full transparency, no censorship and freedom of speech. Only then can we even hope to envisage a less uninviting future.
But it is, dangerously, a debate that the PAP is determined not to have.