A draft version of the security deal, which was initiated by representatives of both sides according to the Solomon Islands government, was signed by China and the Solomons on Thursday.
The Solomon Islands is a nation across an archipelago in the southwest Pacific Ocean, around 2,000km (1,240 miles) northeast of Australia, a country whose ties with China have been in a downward spiral since the pandemic.
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The agreement between Beijing and Honiara is intended to "respond to the Solomon Islands' soft and hard domestic threats", with the Solomons continuing to roll out its national security strategy and uphold its "friends to all and enemies to none" foreign policy, according to Honiara.
In Beijing on Thursday, Chinese foreign affairs spokesman Wang Wenbin said the agreement did not target any third country. He said the Pacific nation was "a stage for international cooperation, but was not any country's 'backyard'".
Wang's remarks were a counter-attack to criticism of the agreement, especially from Australia, whose Prime Minister Scott Morrison said "there is great concern across the Pacific family because we are in constant contact with our Pacific family", according to Sky News.
New Zealand used a similar tone when it said on Monday the country was gravely concerned about possible militarisation of the Pacific following a decision by the Solomon Islands government to form a security partnership with China.
Malcolm Davis, a senior security analyst at the Australian Strategic Policy Institute, said Australia's biggest concern stemmed from the potential for military cooperation between China and the Solomons.
Referring to a paragraph in the draft agreement indicating that China would have the right to deploy Chinese navy and coastguard vessels to the Solomon Islands, Davis said, "this implies, at the very least, some sort of permanent military or paramilitary presence ashore which would, in turn, demand regular support from China".
"So, that amounts to China establishing a military presence in the Solomon Islands, about 2,000km from Australia's eastern seaboard. If that were to happen it would fundamentally change Australia's strategic circumstances for the worse for the first time since the second world war," Davis said.
"Overall, a forward Chinese military base would further undermine Australia's security environment considerably, and generate much greater risks to our defence and security in any future war."
On Friday, the office of Solomon Islands Prime Minister Manasseh Sogavare said the agreement did not invite China to establish a military base in the archipelago.
"[The Solomons] Government is conscious of the security ramification of hosting a military base, and it will not be careless to allow such initiative to take place under its watch," it said.
Sogavare has not released details of the security agreement with China.
Sun Yun, senior fellow and co-director of the East Asia programme and director of the China programme at the Stimson Centre, a US think tank, said the backlash from other countries was not a surprise in the era of strategic competition.
"China's expanding its network of 'friends and partners' just like the US is doing, and Solomon Islands is one of the latest chapters. China gains access and foothold, and that is agency and power," Sun said.
Sun said the sensitivity of the security pact was understandable - China would have the same reaction if it were in Australia's position, since it appeared the action to antagonise Australia in this case was intentional, or perhaps China simply did not mind Australia's reaction in this case.
However, these concerns were perceived a slight in the eyes of Sogavare, who rejected concerns that regional safety would be jeopardised.
"I find it very insulting ... to be branded as unfit to manage our sovereign affairs," he said on Tuesday, adding that the treaty could only be activated at the nation's request.
Sogavare said the Solomons had previously asked Australia to build a naval base but Australia deemed the request inappropriate given it has a defence programme with Papua New Guinea.
The Solomons' diplomatic relations with China were established in September 2019, after the country ditched formal recognition of Taiwan, and the two countries have cooperated on police resources.
According to the Chinese embassy in the Solomons, China sent a batch of anti-riot gear, including helmets, shields, body armour and service raincoats, to the Solomons in late December. The shipment followed demonstrations and riots in the Solomons in late November, during which protesters tried to storm Parliament to depose Sogavare.
Earlier this year, Chinese ambassador Li Ming said "police cooperation between Solomon Islands and China does not conflict with other countries. It adds to collaboration with other countries and is not a zero-sum game."
According to an open source search, Chinese military vessels have not berthed at Solomon's ports in the past.
